Method and apparatus for configuring demodulation reference signal information in wireless cellular communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th generation (5G) communication system with a technology for Internet of Things (IoT) to support higher data rates beyond a 4th generation (4G) system. A method of a UE is provided. The method includes receiving, from a base station, configuration information including first information on a number of an additional demodulation reference signal (DMRS) symbol by higher layer signaling, receiving, from the base station, downlink control information (DCI) including second information on a time domain resource, identifying third information on a duration in symbols of a scheduled physical downlink shared channel (PDSCH) resource based on the second information, identifying a position of a DMRS symbol based on the first information and the third information, and receiving, from the base station, at least one DMRS based on the position of the DMRS symbol.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of U.S. application Ser. No.16/227,604, which was filed in the U.S. Patent and Trademark Office onDec. 20, 2018, and claims priority under 35 U.S.C. § 119 to KoreanPatent Application Serial No. 10-2017-0178380, filed on Dec. 22, 2017,and to Korean Patent Application Serial No. 10-2018-0008885, filed onJan. 24, 2018, in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference.

BACKGROUND 1. Field

The present disclosure relates generally to a wireless communicationsystem and a method and apparatus for configuring demodulation referencesignal (DMRS) related information.

2. Description of Related Art

Since the commercial deployment of 4G communication systems, effortshave been made to develop improved 5G or pre-5G communication systems tomeet the ever increasing demand for wireless data traffic. As such, 5Gor pre-5G communication systems are also called “beyond 4G network” or“post LTE system”. To achieve higher data rates, 5G communicationsystems consider utilization of the mmWave band (e.g., 60 GHz band). Todecrease path loss and increase the transmission distance in the mmWaveband, various technologies including beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas,analog beamforming, and large scale antennas are considered for 5Gcommunication systems. To improve system networks in 5G communicationsystems, technology development is under way regarding evolved smallcells, advanced small cells, cloud radio access networks (RANs),ultra-dense networks, device-to-device (D2D) communication, wirelessbackhaul, moving networks, cooperative communication, coordinatedmulti-points (CoMP), reception interference cancellation, and the like.In addition, advanced coding and modulation (ACM) schemes such as hybridfrequency-shift keying (FSK) and quadrature amplitude modulation (QAM)(FQAM) and sliding window superposition coding (SWSC). Advanced accesstechnologies such as filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) are alsounder development for 5G communication systems.

Meanwhile, the Internet is evolving into the Internet of things (IoT)where distributed elements or things process and exchange information.There has also emerged the Internet of everything (IoE) technology thatcombines IoT technology with big data processing technology throughconnection with cloud servers. To realize IoT services, basetechnologies related to sensing, wired/wireless communication andnetwork infrastructure, service interfacing, and security are needed,and technologies interconnecting things such as sensor networks,machine-to-machine (M2M) or machine type communication (MTC) are underdevelopment. In IoT environments, it is possible to provide intelligentInternet technology services, which collect and analyze data created byinterconnected things to add new values to human life. Throughconvergence and combination between existing information technologiesand various field technologies, IoT technology may be applied to variousareas such as smart homes, smart buildings, smart cities, smart orconnected cars, smart grids, health-care, smart consumer electronics,and advanced medical services.

Accordingly, various attempts are being made to apply 5G communicationsystems to IoT networks. For example, sensor networks and M2M or MTC arebeing realized by use of 5G communication technologies includingbeamforming, MIMO, and array antennas. Application of cloud RANs to bigdata processing described above may be an instance of convergence of 5Gcommunication technology and IoT technology.

In the new radio (NR) system, which is a new 5G communication system,the DMRS configuration is very flexible compared with the existingsystem. Specifically, two different DMRS patterns are supported, thefront-loaded DMRS position can be set differently depending on thesituation, and the number of additional DMRSs can be set in variousmanners. Hence, it is important to configure the DMRS relatedinformation so that the system works well.

SUMMARY

The present disclosure has been made to address at least thedisadvantages described above and to provide at least the advantagesdescribed below. Accordingly, an aspect of the present invention is toprovide a method for effectively configuring DMRS-related information.

In accordance with an aspect of the present disclosure, a method of auser equipment (UE) is provided. The method includes receiving, from abase station, configuration information including first information on anumber of an additional demodulation reference signal (DMRS) symbols byhigher layer signaling, receiving, from the base station, downlinkcontrol information (DCI) including second information on a time domainresource, identifying third information on a duration in symbols of ascheduled physical downlink shared channel (PDSCH) resource based on thesecond information, identifying a position of a DMRS symbol based on thefirst information and the third information, and receiving, from thebase station, at least one DMRS based on the position of the DMRSsymbol.

In accordance with an aspect of the present disclosure, a method of abase station is provided. The method includes transmitting, to a UE,configuration information including first information on a number of anadditional DMRS symbols by higher layer signaling, transmitting, to theUE, DCI including second information on a time domain resource, andtransmitting, to the UE, at least one DMRS based on a position of a DMRSsymbol. The position of the DMRS symbol is identified based on the firstinformation and third information on a duration in symbols of ascheduled PDSCH resource, the third information being identified basedon the second information.

In accordance with an aspect of the present disclosure, a UE in awireless communication system is provided. The UE includes a transceiverand a processor operably connected to the transceiver. The processor isconfigured to control the transceiver to receive, from a base station,configuration information including first information on a number of anadditional DMRS symbols by higher layer signaling, control thetransceiver to receive, from the base station, DCI including secondinformation on a time domain resource, identify third information on aduration in symbols of a scheduled PDSCH resource based on the secondinformation, identify a position of a DMRS symbol based on the firstinformation and the third information, and control the transceiver toreceive, from the base station, at least one DMRS based on the positionof the DMRS symbol.

In accordance with an aspect of the present disclosure, a base stationin a wireless communication system is provided. The base stationincludes a transceiver and a processor operably connected to thetransceiver. The processor is configured to control the transceiver totransmit, to a UE, configuration information including first informationon a number of an additional DMRS symbols by higher layer signaling,transmit, to the UE, DCI including second information on a time domainresource, and transmit, to the UE, at least one DMRS based on a positionof a DMRS symbol. The position of the DMRS symbol is identified based onthe first information and third information on a duration in symbols ofa scheduled PDSCH resource, the third information being identified basedon the second information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the disclosure will be more apparent from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram of a basic configuration of a time-frequency domainin an NR system, according to an embodiment;

FIG. 2 is a diagram of two DMRS patterns, according to an embodiment;

FIGS. 3A, 3B, 3C and 3D are diagrams of locations where DMRSs aretransmitted, according to an embodiment;

FIGS. 4A, 4B, and 4C are diagrams of locations of DMRSs and anadditional DMRS, according to an embodiment;

FIG. 5 is a diagram of a method for setting the number of front-loadedDMRS symbols based on the number of scheduled data symbols, according toan embodiment;

FIG. 6 is a diagram of generation of a DMRS sequence, according to anembodiment;

FIG. 7 is a diagram of a terminal, according to an embodiment; and

FIG. 8 is a diagram of a base station, according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the disclosure will be described herein below withreference to the accompanying drawings. However, the embodiments of thedisclosure are not limited to the specific embodiments and should beconstrued as including all modifications, changes, equivalent devicesand methods, and/or alternative embodiments of the present disclosure.In the description of the drawings, similar reference numerals are usedfor similar elements.

The terms “have,” “may have,” “include,” and “may include” as usedherein indicate the presence of corresponding features (for example,elements such as numerical values, functions, operations, or parts), anddo not preclude the presence of additional features.

The terms “A or B,” “at least one of A or/and B,” or “one or more of Aor/and B” as used herein include all possible combinations of itemsenumerated with them. For example, “A or B,” “at least one of A and B,”or “at least one of A or B” means (1) including at least one A, (2)including at least one B, or (3) including both at least one A and atleast one B.

The terms such as “first” and “second” as used herein may usecorresponding components regardless of importance or an order and areused to distinguish a component from another without limiting thecomponents. These terms may be used for the purpose of distinguishingone element from another element. For example, a first user device and asecond user device indicates different user devices regardless of theorder or importance. For example, a first element may be referred to asa second element without departing from the scope the disclosure, andsimilarly, a second element may be referred to as a first element.

It will be understood that, when an element (for example, a firstelement) is “(operatively or communicatively) coupled with/to” or“connected to” another element (for example, a second element), theelement may be directly coupled with/to another element, and there maybe an intervening element (for example, a third element) between theelement and another element. To the contrary, it will be understoodthat, when an element (for example, a first element) is “directlycoupled with/to” or “directly connected to” another element (forexample, a second element), there is no intervening element (forexample, a third element) between the element and another element.

The expression “configured to (or set to)” as used herein may be usedinterchangeably with “suitable for,” “having the capacity to,” “designedto,” “adapted to,” “made to,” or “capable of” according to a context.The term “configured to (set to)” does not necessarily mean“specifically designed to” in a hardware level. Instead, the expression“apparatus configured to . . . ” may mean that the apparatus is “capableof . . . ” along with other devices or parts in a certain context. Forexample, “a processor configured to (set to) perform A, B, and C” maymean a dedicated processor (e.g., an embedded processor) for performinga corresponding operation, or a generic-purpose processor (e.g., acentral processing unit (CPU) or an application processor (AP)) capableof performing a corresponding operation by executing one or moresoftware programs stored in a memory device.

The terms used in describing the various embodiments of the disclosureare for the purpose of describing particular embodiments and are notintended to limit the disclosure. As used herein, the singular forms areintended to include the plural forms as well, unless the context clearlyindicates otherwise. All of the terms used herein including technical orscientific terms have the same meanings as those generally understood byan ordinary skilled person in the related art unless they are definedotherwise. Terms defined in a generally used dictionary should beinterpreted as having the same or similar meanings as the contextualmeanings of the relevant technology and should not be interpreted ashaving ideal or exaggerated meanings unless they are clearly definedherein. According to circumstances, even the terms defined in thisdisclosure should not be interpreted as excluding the embodiments of thedisclosure.

The term “module” as used herein may, for example, mean a unit includingone of hardware, software, and firmware or a combination of two or moreof them. The “module” may be interchangeably used with, for example, theterm “unit”, “logic”, “logical block”, “component”, or “circuit”. The“module” may be a minimum unit of an integrated component element orapart thereof. The “module” may be a minimum unit for performing one ormore functions or a part thereof. The “module” may be mechanically orelectronically implemented. For example, the “module” according to thedisclosure may include at least one of an application-specificintegrated circuit (ASIC) chip, a field-programmable gate array (FPGA),and a programmable-logic device for performing operations which has beenknown or are to be developed hereinafter.

An electronic device according to the disclosure may include at leastone of, for example, a smart phone, a tablet personal computer (PC), amobile phone, a video phone, an electronic book reader (e-book reader),a desktop PC, a laptop PC, a netbook computer, a workstation, a server,a personal digital assistant (PDA), a portable multimedia player (PMP),a MPEG-1 audio layer-3 (MP3) player, a mobile medical device, a camera,and a wearable device. The wearable device may include at least one ofan accessory type (e.g., a watch, a ring, a bracelet, an anklet, anecklace, a glasses, a contact lens, or a head-mounted device (HMD)), afabric or clothing integrated type (e.g., an electronic clothing), abody-mounted type (e.g., a skin pad, or tattoo), and a bio-implantabletype (e.g., an implantable circuit).

The electronic device may be a home appliance. The home appliance mayinclude at least one of, for example, a television, a digital video disk(DVD) player, an audio, a refrigerator, an air conditioner, a vacuumcleaner, an oven, a microwave oven, a washing machine, an air cleaner, aset-top box, a home automation control panel, a security control panel,a TV box (e.g., Samsung HomeSync™, Apple TV™, or Google TV™), a gameconsole (e.g., Xbox™ and PlayStation™), an electronic dictionary, anelectronic key, a camcorder, and an electronic photo frame.

The electronic device may include at least one of various medicaldevices (e.g., various portable medical measuring devices (a bloodglucose monitoring device, a heart rate monitoring device, a bloodpressure measuring device, a body temperature measuring device, etc.), amagnetic resonance angiography (MRA), a magnetic resonance imaging(MRI), a computed tomography (CT) machine, and an ultrasonic machine), anavigation device, a global positioning system (GPS) receiver, an eventdata recorder (EDR), a flight data recorder (FDR), a vehicleinfotainment device, an electronic device for a ship (e.g., a navigationdevice for a ship, and a gyro-compass), avionics, security devices, anautomotive head unit, a robot for home or industry, an automatic tellermachine (ATM) in banks, point of sales (POS) devices in a shop, or anIoT device (e.g., a light bulb, various sensors, electric or gas meter,a sprinkler device, a fire alarm, a thermostat, a streetlamp, a toaster,a sporting goods, a hot water tank, a heater, a boiler, etc.).

The electronic device may include at least one of a part of furniture ora building/structure, an electronic board, an electronic signaturereceiving device, a projector, and various kinds of measuringinstruments (e.g., a water meter, an electric meter, a gas meter, and aradio wave meter). The electronic device may be a combination of one ormore of the aforementioned various devices. The electronic device mayalso be a flexible device. Further, the electronic device is not limitedto the aforementioned devices, and may include an electronic deviceaccording to the development of new technology.

In the following description, the NR, LTE (long term evolution), andLTE-A (LTE-advanced) systems are taken as an example of the presentdisclosure (LTE systems may include LTE and LTE-A systems). However, thepresent disclosure is applicable to other communication systems usinglicensed and unlicensed bands without significant modification.

In contrast to early wireless communication systems that providedvoice-oriented services only, advanced broadband wireless communicationsystems, such as 3GPP high speed packet access (HSPA) systems, LTE orevolved universal terrestrial radio access (E-UTRA) systems, LTE-Asystems, 3GPP2 high rate packet data (HRPD) systems, ultra mobilebroadband (UMB) systems, and IEEE 802.16e based systems, may providehigh-speed and high-quality packet data services. In addition,communication standards are being developed for 5G or NR systems as thefifth generation wireless communication system.

As a representative example of the broadband wireless communicationsystem, the NR system employs orthogonal frequency division multiplexing(OFDM) in the downlink (DL), and employs both discrete Fourier transformspread OFDM (DFT-S-OFDM) and OFDM in the uplink (UL). UL refers to aradio link through which a terminal (a UE or mobile station (MS)) sendsa data or control signal to a BS (or eNode B), and the downlink refersto a radio link through which a base station sends a data or controlsignal to a terminal. In such multiple access schemes, time-frequencyresources used to carry user data or control information are allocatedso as not to overlap each other (i.e. maintain orthogonality) to therebyidentify the data or control information of a specific user.

FIG. 1 is a diagram of a basic configuration of a time-frequency domain,which is a radio resource region in which data or control channels aretransmitted, in an NR system, according to an embodiment.

In FIG. 1, the horizontal axis denotes the time domain and the verticalaxis denotes the frequency domain. In the time domain, the minimum unitfor downlink transmission is OFDM symbols, the minimum unit for uplinktransmission is OFDM or DFT-S-OFDM symbols, and 14 symbols form one slot(nm) in the case of normal cyclic prefix (NCP). A plurality of symbolsconstitute one subframe 105 according to the numerology of NR. Thelength of a subframe is 1 ms. The number of OFDM or DFT-S-OFDM symbolsconstituting the subframe is shown in Table 1 below.

TABLE 1 Number of OFDM symbols per slot, N_(symb) ^(slot) for NCP μN_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 0 14  10  11 14  20  2 2 14  40  4 3 14  80  8 4 14 160 16 5 14 320 32

In the frequency domain, the minimum unit for transmission is asubcarrier, and the total system transmission bandwidth is composed of atotal N_(RB,x) ^(max,μ)·N_(sc) ^(RB) subcarriers. The value of N_(RB,x)^(max,μ) is given in Table 2 for the uplink and the downlink. N_(sc)^(RB) is the number of subcarriers of the resource block, and theresource block 108 is defined by 12 consecutive subcarriers in thefrequency domain. The basic unit of resources in the time-frequencydomain is a resource element (RE) 112, and the RE may be represented byan OFDM or DFT-S-OFDM symbol index and a subcarrier index.

TABLE 2 μ N_(RB,DL) ^(min,μ) N_(RB,DL) ^(max,μ) N_(RB,UL) ^(min,μ)N_(RB,UL) ^(max,μ) 0 24 275 24 275 1 24 275 24 275 2 24 275 24 275 3 24275 24 275 4 24 138 24 138 5 24  69 24  69

In the NR system, two DMRS patterns are supported.

FIG. 2 is a diagram of two DMRS patterns, according to an embodiment. InFIG. 2, b10 and b20 indicate DMRS configuration type 1, and b10indicates a one-symbol pattern corresponding to one symbol and b20indicates a two-symbol pattern corresponding to two symbols.

The one-symbol pattern (b10, b30) may be referred to as a single-symbolDMRS, and the two-symbol pattern (b20, b40) may be referred to as adouble-symbol DMRS.

DMRS configuration type 1 indicated by b10 and b20 is a DMRS pattern ofcomb 2 structure and can be composed of two code division multiplexing(CDM) groups, and different CDM groups are frequency divisionmultiplexed (FDM). Specifically, in b10 and b20, the portions denoted by210 indicate CDM group 0 and the portions denoted by 200 indicate CDMgroup 1. In the one-symbol pattern of b10, frequency-based CDM isapplied to the same CDM group so that two DMRS ports can be identified,and hence a total of four orthogonal DMRS ports can be set. In b10, theDMRS port identifier (ID) mapped to the CDM group is shown (the actualID may be equal to the number shown plus 1000). In the two-symbolpattern of b20, time and frequency based CDM is applied to the same CDMgroup so that four DMRS ports can be identified, and hence a total ofeight orthogonal DMRS ports can beset. In b20, the DMRS port identifier(ID) mapped to the CDM group is shown (the actual ID may be equal to thenumber shown plus 1000).

In FIG. 2, DMRS configuration type 1 indicated by b30 and b40 is a DMRSpattern of a structure where a frequency domain orthogonal cover code(FD-OCC) is applied to adjacent subcarriers and can be composed of threeCDM groups, and different CDM groups are FDMed. Specifically, in b30 andb40, the portions denoted by 220 indicate CDM group 0, the 210 portionsindicate CDM group 1, and the 200 portions indicate CDM group 0. In theone-symbol pattern of b30, frequency-based CDM is applied to the sameCDM group so that two DMRS ports can be identified, and hence a total ofsix orthogonal DMRS ports can be set. In b30, the DMRS port ID mapped tothe CDM group is shown (the actual ID may be equal to the number shownplus 1000). In the two-symbol pattern of b40, time and frequency basedCDM is applied to the same CDM group so that four DMRS ports can beidentified, and hence a total of 12 orthogonal DMRS ports can be set. Inb40, the DMRS port ID mapped to the CDM group is shown (the actual IDmay be equal to the number shown plus 1000).

As described above, two different types of DMRS patterns can be set inthe NR system. For example, in FIG. 2, there may be DMRS configurationtype 1 indicated by b10 and b20 and DMRS configuration type 2 indicatedby b30 and b40.

Also, the DMRS pattern can be a single-symbol DMRS corresponding to onesymbol or a double-symbol DMRS corresponding to two neighboring symbols.For example, in FIG. 2, there may be single-symbol DMRSs indicated byb10 and b30 and double-symbol DMRSs indicated by b20 and b40.

It is possible to schedule the scheduled DMRS port numbers and to signalthe number of the scheduled CDM groups for rate matching of the physicaldownlink shared channel (PDSCH). With CP (cyclic prefix)-OFDM, the twotypes of DMRS patterns are supported in the downlink and the uplink.With DFT-S-OFDM, only DMRS configuration type 1 of the DMRS patterntypes is supported in the uplink.

The NR system supports front-loaded and additional DMRSs. Thefront-loaded DMRS refers to the first DMRS in time among the front-mostsymbols, and the additional DMRS refers to the DMRS appearing in thesymbols after the front-loaded DMRS. The number of additional DMRS inthe NR system can be from zero to three.

Furthermore, when an additional DMRS is configured, the same type as thefront-loaded DMRS is assumed. For example, the additional DMRS isconfigured to have the same DMRS configuration type (type 1 or type 2)as the front-loaded DMRS. If the front-loaded DMRS is a one-symbolpattern (b10 and b30), the additional DMRS is also configured asone-symbol pattern, and if the front-loaded DMRS is a two-symbol pattern(b20 and b40), the additional DMRS is also configured as a two-symbolpattern.

an embodiment. FIGS. 4A to 4C are diagrams of locations of DMRSs and anadditional DMRS, according to an embodiment.

The portions denoted by 300 and the portions denoted by 400 in the DMRSposition related drawings indicate symbols via which the DMRS istransmitted, and a configured DMRS pattern (b10, b20, b30 or b40) of thetwo types of DMRS patterns described with reference to FIG. 2 can betransmitted at the location indicated by the portions 220.

For slot-based scheduling as shown in FIGS. 3A to 3D, the symbol numbercan be indexed relative to the first OFDM symbol of the slot. Fornon-slot-based scheduling as shown in FIGS. 4A to 4C, the symbol numbercan be indexed relative to the first scheduled OFDM symbol.

In the NR system, the position of the DMRS can be set separately forPDSCH mapping type A and PDSCH mapping type B, and it can also be setseparately for PUSCH mapping type A and PUSCH mapping type B. Moredetailed information is described in the following embodiments. Further,additional settings for the DMRS information are described in moredetail in the following embodiments.

Hereinafter, embodiments of the present invention are described indetail with reference to the accompanying drawings. The followingdescription is focused on the NR system. However, it should beunderstood by those skilled in the art that the subject matter of thepresent invention is applicable to other communication systems havingsimilar technical backgrounds and channel configurations withoutsignificant modifications departing from the scope of the presentinvention. Descriptions of well-known functions and structuresincorporated herein may be omitted to avoid obscuring the subject matterof the present invention. Particular terms may be defined to describethe invention in the best manner. Hence, the meaning of specific termsor words used in the specification and the claims should be construed inaccordance with the spirit of the present invention. In the followingdescription, the base station (BS) may be at least one of eNode B, NodeB, a radio access unit, a base station controller, and a node on anetwork. The terminal may be a user equipment (UE), a mobile station(MS), a cellular phone, a smartphone, a computer, or a multimedia systemcapable of performing communication functions. The uplink (UL) refers toa wireless transmission path through which the terminal transmits asignal to the base station. In the above description, the one-symbolpattern (b10 and b30 of FIG. 2) among the DMRS patterns may be referredto as a single-symbol DMRS and the two-symbol pattern (b20 and b40 ofFIG. 2) may be referred to as a double-symbol DMRS.

In the following description, the first embodiment of the presentinvention relates to a method for determining the DMRS positionconfiguration according to the length of DL or UL symbols that can beassigned to the slot. The second embodiment relates to a method fordetermining the DMRS position configuration according to the length ofactually scheduled DL or UL symbols. The third embodiment proposes amethod of configuring DMRS information via RRC. Although the number ofbits required to indicate the DMRS ports may vary according to the DMRSconfiguration, the fourth embodiment proposes a method of composing aDMRS port indication table to keep the DCI overhead the same.

The fifth embodiment proposes a method of determining the length of aDMRS sequence to be generated.

First Embodiment

The first embodiment proposes a method for determining the DMRS positionconfiguration described above according to the length of DL or ULsymbols that can be assigned to the slot. In the first embodiment, theDMRS position for the PDSCH in the downlink can be set as follows.

DMRS position setting for PDSCH

-   -   PDSCH mapping type A        -   The position of the front-loaded DMRS is fixed at the third            or fourth symbol        -   The position of the additional DMRS is described in FIGS. 3A            to 3D    -   PDSCH mapping type B        -   The position of the front-loaded DMRS is the first scheduled            symbol        -   No additional DMRS for 2/4 symbol non-slot based scheduling        -   For non-slot based scheduling of different symbol lengths            including 7 symbol non-slot based scheduling, refer to FIGS.            4A to 4C for the position of the additional DMRS

The DMRS position setting for the PDSCH can be divided according toPDSCH mapping types A and B. Specifically, PDSCH mapping type A can beinterpreted as a DMRS position setting scheme based on slot-basedscheduling, and PDSCH mapping type B can be interpreted as a DMRSposition setting scheme based on non-slot based scheduling.

The position of the front-loaded DMRS is set differently according toPDSCH mapping type A or B. More specifically, in the case of PDSCHmapping type A, the position of the front-loaded DMRS is fixed at thethird or fourth symbol. With PDSCH mapping type B, the position of thefront-loaded DMRS is located at the first symbol of the scheduled PDSCH.

In FIGS. 3A to 3D, for PDSCH mapping type A, the position of thefront-loaded DMRS and the position of the additional DMRS are showntogether. The portions denoted by 300 indicate the position of a symbolthrough which the DMRS is transmitted and some of the subcarriers may beused for PDSCH transmission depending on the number of CDM groups used.The portions denoted by 310 a indicate a possible region where the PDSCHcan be transmitted according to the method proposed in the firstembodiment. For example, the actual PDSCH scheduling may be smaller thanthe region where the PDSCH can be transmitted. The portions denoted by320 indicate a region where the PDSCH is not transmitted. For example,the 320 portion can be used for the PUSCH region. The portions denotedby 330 indicate a region where the physical downlink control channel(PDCCH) can be transmitted in the case of DL, and this portion can alsobe used for PDSCH transmission if the PDCCH is not transmitted (and viceversa for PUSCH).

FIGS. 3A to 3D show the position where the DMRS is transmitted based onthe possible region in which the PDSCH can be transmitted according tothe method proposed in the first embodiment of the present invention.

FIGS. 3A to 3D illustrate locations where the DMRS is transmittedaccording to various embodiments of the present invention. In FIGS. 3Aand 38, c0 to c52 indicate possible DMRS positions when the one-symbolfront loaded DMRS is configured to transmit the DMRS via one symbol. InFIG. 3D, c60 to c74 indicate possible DMRS positions when the two-symbolfront loaded DMRS is configured to transmit the DMRS via two adjacentsymbols.

In FIG. 3A, c0 to c25 indicate possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured, c0to c15 indicate possible positions of the additional DMRS when the frontloaded DMRS is set at the fourth symbol, and c20 to c25 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the third symbol. More specifically, in c0 and c20, the portionof the slot except for the last five symbols indicated in 320 is thepossible region where the PDSCH can be transmitted, and the additionalDMRS is transmitted via the eighth symbol. In c11 and c21, the portionof the slot except for the last four symbols indicated in 320 is thepossible region where the PDSCH can be transmitted, and the additionalDMRS is transmitted via the tenth symbol. In c12 and c22, the portion ofthe slot except for the last three symbols indicated in 320 is thepossible region where the PDSCH can be transmitted, and the additionalDMRS is transmitted via the tenth symbol. In c13 and c23, the portion ofthe slot except for the last two symbols indicated in 320 is thepossible region where the PDSCH can be transmitted, and the additionalDMRS is transmitted via the 10th symbol. In c14 and c24, the portion ofthe slot except for the last symbol indicated in 320 is the possibleregion where the PDSCH can be transmitted, and the additional DMRS istransmitted via the 12th symbol. In c15 and c25, the whole portion ofthe slot is the possible region where the PDSCH can be transmitted, andthe additional DMRS is transmitted via the 12th symbol.

In FIG. 3B, c30 to c44 indicate possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured,c30 to c34 indicate possible positions of the additional DMRS when thefront loaded DMRS is set at the 4th symbol, and c40 to c44 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the 3rd symbol. More specifically, in c30 and c40, the portion ofthe slot except for the last four symbols indicated in 320 is thepossible region where the PDSCH can be transmitted, and the additionalDMRS is transmitted via the 7th and 10th symbols. In c31 and c41, theportion of the slot except for the last three symbols indicated in 320is the possible region where the PDSCH can be transmitted, and theadditional DMRS is transmitted via the 7th and 10th symbols. In c32 andc42, the portion of the slot except for the last two symbols indicatedin 320 is the possible region where the PDSCH can be transmitted, andthe additional DMRS is transmitted via the 7th and 10th symbols. In c33and c43, the portion of the slot except for the last symbol indicated in320 is the possible region where the PDSCH can be transmitted, and theadditional DMRS is transmitted via the 8th and 12th symbols. In c34 andc44, the whole portion of the slot is the possible region where thePDSCH can be transmitted, and the additional DMRS is transmitted via the8th and 12th symbols.

In FIG. 3C, c50 to c52 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.This is possible when the front loaded DMRS is configured at the 3rdsymbol in consideration of the actual usage scenario as shown in FIG.3C. More specifically, when three additional DMRSs are configured asshown by c50 to c52, the additional DMRS is transmitted via the 6th,9th, and 12th symbols regardless of the possible region where the PDSCHcan be transmitted.

In FIG. 3D, c60 to c74 indicate possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured.Considering the DMRS overhead and the actual usage scenario, at most oneadditional DMRS can be configured when the two-symbol front loaded DMRSis configured. In c60 to c64 indicate possible positions of theadditional DMRS when the first front loaded DMRS symbol is configured atthe 4th symbol. In c70 to c74 indicate possible positions of theadditional DMRS when the first front loaded DMRS symbol is configured atthe 3rd symbol. More specifically, in c60 and c70, the portion of theslot except for the last four symbols indicated in 320 is the possibleregion where the PDSCH can be transmitted, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c61 and c71, theportion of the slot except for the last three symbols indicated in 320is the possible region where the PDSCH can be transmitted, and the firstsymbol of the additional DMRS is transmitted via the 9th symbol. In c62and c72, the portion of the slot except for the last two symbolsindicated in 320 is the possible region where the PDSCH can betransmitted, and the first symbol of the additional DMRS is transmittedvia the 9th symbol. In c63 and c73, the portion of the slot except forthe last symbol indicated in 320 is the possible region where the PDSCHcan be transmitted, and the first symbol of the additional DMRS istransmitted via the 11th symbol. In c64 and c74, the whole portion ofthe slot is the possible region where the PDSCH can be transmitted, andthe first symbol of the additional DMRS is transmitted via the 11thsymbol.

On the other hand, for PDSCH mapping type B, the position of thefront-loaded DMRS is set at the first scheduled symbol. In the case of 2or 4 symbol non-slot based scheduling, no additional DMRS is configuredowing to the short symbol length and DMRS overhead. For non-slot basedscheduling of different lengths including 7-symbol non-slot basedscheduling, a description is given of the position of the additionalDMRS with reference to FIGS. 4A to 4C.

FIGS. 4A to 4C show the locations of DMRSs and an additional DMRSaccording to an embodiment. In FIGS. 4A to 4C, the portions denoted by400 indicate DMRS location (e.g., the part of subcarriers in DMRS symbolthat can be used for PDSCH transmission). The portions demoted by 410indicate a possible location of the PDSCH. In FIGS. 4A and 4B, d10 tod32 indicate possible DMRS positions when the one-symbol front loadedDMRS is configured. In FIG. 4C, d40 to d42 indicate possible DMRSpositions when the two-symbol front loaded DMRS is configured.

In FIG. 4A, d10 to d13 indicate the possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured. Ind10, when the possible region where the PDSCH can be transmitted isconfigured in the 5th to 7th symbols, the additional DMRS is transmittedvia the 5th symbol. In d11, when the possible region where the PDSCH canbe transmitted is configured in the 8th and 9th symbols, the additionalDMRS is transmitted via the 7th symbol. In d12, when the possible regionwhere the PDSCH can be transmitted is configured in the 10th and 11thsymbols, the additional DMRS is transmitted via the 9th symbol. In d13,when the possible region where the PDSCH can be transmitted isconfigured in the 12th and 13th symbols, the additional DMRS istransmitted via the 11th symbol.

In FIG. 4B, d20 to d22 indicate the possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured. Ind20, when the possible region where the PDSCH can be transmitted isconfigured in the 8th and 9th symbols, the additional DMRS istransmitted via the 4th and 7th symbols. In d21, when the possibleregion where the PDSCH can be transmitted is configured in the 10th and11th symbols, the additional DMRS is transmitted via the 5th and 9thsymbols. In d22, when the possible region where the PDSCH can betransmitted is configured in the 12th and 13th symbols, the additionalDMRS is transmitted via the 6th and 11th symbols.

In FIG. 4B, d30 to d32 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.The additional DMRS is transmitted via the 4th, 7th, and 10th symbolsregardless of the possible region where the PDSCH can be transmitted.

In FIG. 4C, d40 to d42 indicate the possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured. Ind40, when the possible region where the PDSCH can be transmitted isconfigured in the 8th and 9th symbols, the first symbol of theadditional DMRS is transmitted via the 6th symbol. In d41, when thepossible region where the PDSCH can be transmitted is configured in the10th and 11th symbols, the first symbol of the additional DMRS istransmitted via the 8th symbol. In d42, when the possible region wherethe PDSCH can be transmitted is configured in the 12th and 13th symbols,the first symbol of the additional DMRS is transmitted via the 10thsymbol.

Based on the above description, for PDSCH mapping types A and B, theDMRS position can be set as follows according to the first embodiment.

For PDSCH, the reference point for l and the position l₀ of the firstDM-RS symbol depend on the mapping type. For PDSCH mapping type A

-   -   l is defined relative to the start of the slot    -   l₀=3 if the higher-layer parameter DL-DMRS-typeA-pos equals 3        and l₀=2 otherwise

for PDSCH mapping type B:

-   -   l is defined relative to the start of the scheduled PDSCH        resources    -   l₀=0

Table 3 shows the positions of the front-loaded and additional DMRSs forPDSCH mapping types A and B in the case of a single-symbol DMRS.

TABLE 3 PDSCH DMRS positions for single-symbol DMRS DM-RS positions l⁻Duration of PDSCH mapping type A PDSCH mapping type B PDSCHDL-DMRS-add-pos DL-DMRS-add-pos transmission 0 1 2 3 0 1 2 3 ≤6 l₀ — — —l₀  7 l₀ — — — l₀ l₀, 4  8 l₀ — — — l₀ l₀, 6 l₀, 3, 6 —  9 l₀ l₀, 7 — —l₀ l₀, 6 l₀, 3, 6 — 10 l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 911 l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 12 l₀ l₀, 9 l₀, 6,9 2, 5, l₀ l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 13 l₀ l₀, 11 l₀, 7, 11 2,5, l₀ l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 14 l₀ l₀, 11 l₀, 7, 11 2, 5, l₀8, 11

Table 4 shows the positions of the front-loaded and additional DMRSs forPDSCH mapping types A and B in the case of a double-symbol DMRS.

TABLE 4 PDSCH DMRS positions l⁻ for double-symbol DMRS DM-RS positionsl⁻ Duration of PDSCH mapping type A PDSCH mapping type B PDSCHDL-DMRS-add-pos DL-DMRS-add-pos transmission 0 1 2 0 1 2 ≤8 l₀ — l₀  8l₀ — l₀ l₀, 5  9 l₀ — l₀ l₀, 5 10 l₀ l₀, 8 l₀ l₀, 7 11 l₀ l₀, 8 l₀ l₀, 712 l₀ l₀, 8 l₀ l₀, 9 13 l₀ l₀, 10 l₀ l₀, 9 14 l₀ l₀, 10 l₀

Table 5 shows the DMRS time index and possible antenna port numbers forthe single-symbol DMRS and double-symbol DMRS.

TABLE 5 PDSCH DMRS time index l′ and antenna ports p Single or doubleSupported antenna ports p symbol DM-RS l′ Configuration type 1Configuration type 2 single 0 1000-1003 1000-1005 double 0, 1 1000-10071000-1011

Based on the definition of the DMRS reference point l and the DMRSposition information l and l′ obtained from Tables 3, 4 and 5, the DMRSreference point for the PDSCH is set by l=l+l′.

Next, in the first embodiment, the DMRS position for the PUSCH (withouta hop) in the uplink can be set as follows.

DMRS position setting for PUSCH (without a hop)

-   -   PUSCH mapping type A        -   The position of the front-loaded DMRS is fixed at the 3rd or            4th symbol            -   Considering a common DMRS structure for DL or UL, if                fixed at the 3rd symbol for DL, it is also fixed at the                3rd symbol for UL, and if fixed at the 4th symbol for                DL, it is also fixed at the 4th symbol for UL        -   For the position of the additional DMRS, refer to FIGS. 3A            to 3D    -   PUSCH mapping type B        -   The position of the front-loaded DMRS is the first scheduled            symbol        -   No additional DMRS for 2 or 4 symbol non-slot based            scheduling        -   For non-slot based scheduling of different symbol lengths            including 7 symbol non-slot based scheduling, refer to FIGS.            4A to 4C for the position of the additional DMRS

The DMRS position setting for the PUSCH (without a hop) can be dividedaccording to PUSCH mapping types A and B. Specifically, PUSCH mappingtype A can be interpreted as a DMRS position setting scheme based onslot-based scheduling, and PUSCH mapping type B can be interpreted as aDMRS position setting scheme based on non-slot based scheduling. Theposition of the front-loaded DMRS is set differently according to PUSCHmapping type A or B. More specifically, in the case of PUSCH mappingtype A, the position of the front-loaded DMRS is fixed at the third orfourth symbol. In the case of PUSCH mapping type B, the position of thefront-loaded DMRS is located at the first symbol of the scheduled PDSCH.For PUSCH mapping type A, the position of the front-loaded DMRS and theposition of the additional DMRS may be given together as shown in FIGS.3A to 3D.

In FIGS. 3A to 3D, the portions denoted by 300 indicate the position ofa symbol through which the DMRS is transmitted and some of thesubcarriers may be used for PUSCH transmission depending on the numberof CDM groups used. The portions denoted by 310 indicate a possibleregion where the PUSCH can be transmitted according to the methodproposed in the first embodiment. For example, the actual PUSCHscheduling may be smaller than the region where the PUSCH can betransmitted. The portions denoted by 320 indicate a region where thePUSCH is not transmitted. For example, the 320 portion can be used forSRS transmission and a short PUCCH region. In FIGS. 3A to 3D, theportions denoted by 330 indicate a region where the PDCCH can betransmitted in the case of DL, and this portion can also be used forPUSCH transmission in the case of UL.

FIGS. 3A to 3D show the position where the DMRS is transmitted based onthe possible region where the PUSCH can be transmitted according to themethod proposed in the first embodiment of the present invention.

In FIGS. 3A and 3B, c0 to c52 indicate possible DMRS positions when theone-symbol front loaded DMRS is configured. In FIG. 3D, c60 to c74indicate possible DMRS positions when the two-symbol front loaded DMRSis configured.

In FIG. 3A, c0 to c25 indicate possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured, c0to c15 indicate possible positions of the additional DMRS when the frontloaded DMRS is set at the fourth symbol, and c20 to c25 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the third symbol. More specifically, in c10 and c20, the portionof the slot except for the last five symbols indicated in 320 is thepossible region where the PUSCH can be transmitted, and the additionalDMRS is transmitted via the 8th symbol. In c11 and c21, the portion ofthe slot except for the last four symbols indicated in 320 is thepossible region where the PUSCH can be transmitted, and the additionalDMRS is transmitted via the 10th symbol. In c12 and c22, the portion ofthe slot except for the last three symbols indicated in 320 is thepossible region where the PUSCH can be transmitted, and the additionalDMRS is transmitted via the 10th symbol. In c13 and c23, the portion ofthe slot except for the last two symbols indicated in 320 is thepossible region where the PUSCH can be transmitted, and the additionalDMRS is transmitted via the 10th symbol. In c14 and c24, the portion ofthe slot except for the last symbol indicated in 320 is the possibleregion where the PUSCH can be transmitted, and the additional DMRS istransmitted via the 12th symbol. In c15 and c25, the whole portion ofthe slot is the possible region where the PUSCH can be transmitted, andthe additional DMRS is transmitted via the 12th symbol.

In FIG. 3B, c30 to c44 indicate possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured,c30 to c34 indicate possible positions of the additional DMRS when thefront loaded DMRS is set at the 4th symbol, and c40 to c44 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the 3rd symbol. More specifically, in c30 and c40, the portion ofthe slot except for the last four symbols indicated in 320 is thepossible region where the PUSCH can be transmitted, and the additionalDMRS is transmitted via the 7th and 10th symbols. In c31 and c41, theportion of the slot except for the last three symbols indicated in 320is the possible region where the PUSCH can be transmitted, and theadditional DMRS is transmitted via the 7th and 10th symbols. In c32 andc42, the portion of the slot except for the last two symbols indicatedin 320 is the possible region where the PUSCH can be transmitted, andthe additional DMRS is transmitted via the 7th and 10th symbols. In c33and c43, the portion of the slot except for the last symbol indicated in320 is the possible region where the PUSCH can be transmitted, and theadditional DMRS is transmitted via the 8th and 12th symbols. In c34 andc44, the whole portion of the slot is the possible region where thePUSCH can be transmitted, and the additional DMRS is transmitted via the8th and 12th symbols.

In FIG. 3C, c50 to c52 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.This is possible when the front loaded DMRS is configured at the 3rdsymbol in consideration of the actual usage scenario as shown in FIG.3C. More specifically, when three additional DMRSs are configured asshown by c50 to c52, the additional DMRS is transmitted via the 6th,9th, and 12th symbols regardless of the possible region where the PUSCHcan be transmitted.

In FIG. 3D, c60 to c74 indicate possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured.Considering the DMRS overhead and the actual usage scenario, at most oneadditional DMRS can be configured when the two-symbol front loaded DMRSis configured. In c60 to c64 indicate possible positions of theadditional DMRS when the first front loaded DMRS symbol is configured atthe 4th symbol. In addition, c70 to c74 indicate possible positions ofthe additional DMRS when the first front loaded DMRS symbol isconfigured at the 3rd symbol. More specifically, in c60 and c70, theportion of the slot except for the last four symbols indicated in 320 isthe possible region where the PUSCH can be transmitted, and the firstsymbol of the additional DMRS is transmitted via the 9th symbol. In c61and c71, the portion of the slot except for the last three symbolsindicated in 320 is the possible region where the PUSCH can betransmitted, and the first symbol of the additional DMRS is transmittedvia the 9th symbol. In c62 and c72, the portion of the slot except forthe last two symbols indicated in 320 is the possible region where thePUSCH can be transmitted, and the first symbol of the additional DMRS istransmitted via the 9th symbol. In c63 and c73, the portion of the slotexcept for the last symbol indicated in 320 is the possible region wherethe PUSCH can be transmitted, and the first symbol of the additionalDMRS is transmitted via the 11th symbol. In c64 and c74, the wholeportion of the slot is the possible region where the PUSCH can betransmitted, and the first symbol of the additional DMRS is transmittedvia the 11th symbol.

On the other hand, for PUSCH mapping type B, the position of thefront-loaded DMRS is set at the first scheduled symbol. In the case of 2or 4 symbol non-slot based scheduling, no additional DMRS is configuredowing to the short symbol length and DMRS overhead. For non-slot basedscheduling of different lengths including 7-symbol non-slot basedscheduling, a description is given of the position of the additionalDMRS with reference to FIGS. 4A to 4C.

In FIGS. 4A and 4B, d10 to d32 indicate possible DMRS positions when theone-symbol front loaded DMRS is configured. In FIG. 4C, d40 to d42indicate possible DMRS positions when the two-symbol front loaded DMRSis configured.

In FIG. 4A, d10 to d13 indicate the possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured. Ind10, when the possible region where the PUSCH can be transmitted isconfigured in the 5th to 7th symbols, the additional DMRS is transmittedvia the 5th symbol. In d11, when the possible region where the PUSCH canbe transmitted is configured in the 8th and 9th symbols, the additionalDMRS is transmitted via the 7th symbol. In d12, when the possible regionwhere the PUSCH can be transmitted is configured in the 10th and 11thsymbols, the additional DMRS is transmitted via the 9th symbol. In d13,when the possible region where the PUSCH can be transmitted isconfigured in the 12th and 13th symbols, the additional DMRS istransmitted via the 11th symbol.

In FIG. 4B, d20 to d22 indicate the possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured. Ind20, when the possible region where the PUSCH can be transmitted isconfigured in the 8th and 9th symbols, the additional DMRS istransmitted via the 4th and 7th symbols. In d21, when the possibleregion where the PUSCH can be transmitted is configured in the 10th and11th symbols, the additional DMRS is transmitted via the 5th and 9thsymbols. In d22, when the possible region where the PUSCH can betransmitted is configured in the 12th and 13th symbols, the additionalDMRS is transmitted via the 6th and 11th symbols.

In FIG. 4B, d30 to d32 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.The additional DMRS is transmitted via the 4th, 7th, and 10th symbolsregardless of the possible region where the PUSCH can be transmitted.

In FIG. 4C, d40 to d42 indicate the possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured. Ind40, when the possible region where the PUSCH can be transmitted isconfigured in the 8th and 9th symbols, the first symbol of theadditional DMRS is transmitted via the 6th symbol. In d41, when thepossible region where the PUSCH can be transmitted is configured in the10th and 11th symbols, the first symbol of the additional DMRS istransmitted via the 8th symbol. In d42, when the possible region wherethe PUSCH can be transmitted is configured in the 12th and 13th symbols,the first symbol of the additional DMRS is transmitted via the 10thsymbol. Based on the above description, for PUSCH mapping types A and B,the DMRS position can be set as follows according to the firstembodiment.

For PUSCH, the reference point for l and the position l₀ of the firstDM-RS symbol depend on the mapping type:

-   -   for PUSCH mapping type A:        -   l is defined relative to the start of the slot        -   l₀=3 if the higher-layer parameter DL-DMRS-typeA-pos equals            3 and l₀=2 otherwise    -   for PUSCH mapping type B:        -   l is defined relative to the start of the scheduled PUSCH            resources        -   l₀=0

Table 6 shows the positions of the front-loaded and additional DMRSs forPUSCH mapping types A and B in the case of a single-symbol DMRS.

TABLE 6 PUSCH DMRS positions l⁻ for single-symbol DMRS DM-RS positionsl⁻ PUSCH PUSCH mapping type A PUSCH mapping type B duration inDL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 3 0 1 2 3 ≤7 l₀ — — — l₀l₀, 4 — —  8 l₀ — — — l₀ l₀, 6 l₀, 3, 6 —  9 l₀ l₀, 7 — — l₀ l₀, 6 l₀,3, 6 — 10 l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 11 l₀ l₀, 9l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 12 l₀ l₀, 9 l₀, 6, 9 2, 5, l₀l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 13 l₀ l₀, 11 l₀, 7, 11 2, 5, l₀ l₀,10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 14 l₀ l₀, 11 l₀, 7, 11 2, 5, — — — — 8,11

Table 7 shows the positions of the front-loaded and additional DMRSs forPUSCH mapping types A and B in the case of a double-symbol DMRS.

TABLE 7 PUSCH DMRS positions l⁻ for double-symbol DMRS DM-RS positionsl⁻ PUSCH PUSCH mapping type A PUSCH mapping type B duration inDL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 3 0 1 2 3 ≤7 l₀ — l₀ —  8l₀ — l₀ l₀, 5  9 l₀ — l₀ l₀, 5 10 l₀ l₀, 8 l₀ l₀, 7 11 l₀ l₀, 8 l₀ l₀, 712 l₀ l₀, 8 l₀ l₀, 9 13 l₀ l₀, 10 l₀ l₀, 9 14 l₀ l₀, 10 — —

Table 8 shows the DMRS time index and possible antenna port numbers forthe single-symbol DMRS and double-symbol DMRS.

TABLE 8 PUSCH DMRS time index l′ and antenna ports p Supported antennaports p DM-RS duration l′ Configuration type 1 Configuration type 2single-symbol 0 1000-1003 1000-1005 DM-RS double-symbol 0, 1 1000-10071000-1011 DM-RS

Based on the definition of the DMRS reference point l and the DMRSposition information l and l′ obtained from Tables 1, 2 and 3, the DMRSreference point for the PDSCH is set by l=l+l′.

Hereinabove, a description is given of the DMRS position setting methodfor the PUSCH (without a hop). Next, for the PUSCH (with a hop), theDMRS position can be set as follows.

DMRS position setting for PUSCH (with a hop)

-   -   First hop        -   PUSCH mapping type A            -   The position of the one-symbol front loaded DMRS is                fixed at the 3rd or 4th symbol            -   If 5 or more symbols are scheduled relative to the                front-loaded DMRS, the position of the additional DMRS                is at the 5th symbol relative to the front-loaded DMRS.                Otherwise, no additional DMRS is used        -   PUSCH mapping type B            -   The position of the front-loaded DMRS is the first                scheduled symbol            -   If 5 or more symbols are scheduled relative to the                front-loaded DMRS, the position of the additional DMRS                is at the 5th symbol relative to the front-loaded DMRS.                Otherwise, no additional DMRS is used        -   Second hop            -   The position of the front-loaded DMRS is at the first                symbol of the PUSCH corresponding to the second hop            -   If 5 or more symbols are scheduled relative to the                front-loaded DMRS corresponding to the second hop, the                position of the additional DMRS is at the 5th symbol                relative to the front-loaded DMRS. Otherwise, no                additional DMRS is used    -   The same DMRS position is configured for both CP-OFDM and        DFT-S-OFDM

As described in the first embodiment, when the DMRS position setting isdetermined according to the DL or UL symbol length assignable to theslot, if the actual scheduled PDSCH or PUSCH region is smaller than theassignable PDSCH or PUSCH region, there may be a problem in configuringthe DMRS position. For example, in c15 of FIG. 3A, an ambiguity aboutthe additional DMRS occurs when the PDSCH is scheduled ahead of the 12thsymbol where the additional DMRS is to be transmitted. In such a case,the following scheme can be considered.

Handling ambiguity about additional DMRS when actual scheduling issmaller than PDSCH or PUSCH region.

-   -   Alternative-1: the UE does not expect to be configured with such        a scenario.    -   Alternative-2: if the UE has been configured with X additional        DMRSs and if the PDSCH/PUSCH size is smaller than the minimum        size that has been specified (See Table 1, 2, 4, 5), then a DMRS        pattern with X−1 additional DMRSs will be used. The UE does not        expect to be configured with any other scenario.    -   Alternative-3: the number of additional DMRSs is determined to        be the maximum number of additional DMRSs, which the PDSCH/PUSCH        region supports (See Tables 1, 2, 4, 5).

Referring to c15 of FIG. 3A, in Alternative 1, the UE does not expectthe PDSCH or the PUSCH to be scheduled ahead of the 12th symbol. Thisplaces a restriction on scheduling. That is, when DMRS information isconfigured as in c15 of FIG. 3A, there is a restriction that schedulingof the PDSCH or PUSCH should include up to the 12th symbol. InAlternative 2, if the PDSCH or PUSCH is scheduled ahead of the 12thsymbol in c15 of FIG. 3A, the additional DMRS located at the 12th symbolis punctured and only the DMRS in the scheduled region is utilized. InAlternative 3, if the PDSCH or PUSCH is scheduled up to the 11th symbolin c15 of FIG. 3A, the additional DMRS is assumed to be located at the10th symbol as shown in c13 of FIG. 3A.

In the first embodiment, the DMRS position setting is determinedaccording to the DL or UL symbol length assignable to the slot. The DMRSinformation can be configured as follows. In the NR system, theDMRS-related information can be identified through the physicalbroadcast channel (PBCH), radio resource control (RRC), group commonDCI, and UE-specific DCI, and each signaling may include the followinginformation.

-   -   When the position of the front-loaded DMRS is fixed at the 3rd        or 4th symbol through the PBCH, receive an indication of whether        the front-loaded DMRS is located at the 3rd symbol or at the 4th        symbol    -   Slot format indication (SFI) information can be configured via        cell-specific RRC, and the SFI information is notified via        system information (SIB2)    -   The SFI information may be configured and notified via        UE-specific RRC    -   The SFI information may be dynamically configured and notified        via group common DCI    -   Some or all of the following information may be configured and        received via UE specific DCI        -   Information about PDSCH mapping types A and B/PUSCH mapping            types A and B            -   Indication of mapping type A or B        -   PDSCH or PUSCH scheduling information            -   Start position and duration of PDSCH or PUSCH        -   Indication of DMRS port information            -   Scheduled DMRS port information            -   Number of CDM groups scheduled together for PDSCH rate                matching            -   Indication of whether front-loaded DMRS is one-symbol                DMRS or two-symbol DMRS            -   Frequency hopping enabling or disabling    -   Prior to RRC setup, the DMRS configuration for PDSCH or PUSCH is        subdivided as follows according to the configured SFI        information and DCI scheduling information        -   DMRS pattern is assumed to be DMRS-config-type 1        -   In the case of slot-based scheduling, a one-symbol            front-loaded DMRS and two additional DMRSs are configured by            default; for their positions, refer to PDSCH mapping type A            in Table 3 (for PDSCH DMRS) and PUSCH mapping type A in            Table 6 (for PUSCH DMRS).        -   In the case of 2 or 4-symbol non-slot-based scheduling, only            the one-symbol front-loaded DMRS is configured and no            additional DMRS is configured.        -   In the case of non-slot based scheduling of different symbol            lengths including 7-symbol non-slot based scheduling, a            single-symbol front-loaded DMRS and one single-symbol            additional DMRS are configured; for their positions, refer            to PDSCH mapping type B in Table 3 (for PDSCH DMRS) and            PUSCH mapping type B in Table 6 (for PUSCH DMRS).        -   In the case of PUSCH (with a hop), Mode 1 (intra-slot FH            only) is assumed when frequency hopping is enabled by the            DCI, and no additional DMRS is configured for PUSCH mapping            type A and the additional DMRS is configured by default for            PUSCH mapping type B.        -   If the actual scheduling is smaller than the PDSCH or PUSCH            region, one of the proposed methods can be considered to            resolve the ambiguity about the additional DMRS.    -   Prior to RRC setup, PDSCH DMRS transmission is allowed only for        single-user multi-input-multi-output (SU-MIMO) with DMRS port 0,        and FDM between the PDSCH symbol and the DMRS symbol is not        allowed for slot-based scheduling and 4 or 7-symbol        non-slot-based scheduling. However, FDM between the PDSCH symbol        and the DMRS symbol is allowed for 2-symbol non-slot-based        scheduling.    -   Prior to RRC setup, PUSCH DMRS transmission is allowed only for        SU-MIMO with DMRS port 0, and FDM between the PDSCH symbol and        the DMRS symbol is not allowed.    -   After RRC setup, the DMRS configuration for PDSCH or PUSCH is        subdivided as follows according to the DMRS information        configured via RRC, configured SFI information, and DCI        scheduling information        -   DMRS information configured via RRC            -   DMRS configuration type (DMRS-config-type)                -   DMRS-config-type=1 or 2            -   The maximum number of the front-loaded DMRS symbols                (DMRS-max-len)                -   DMRS-max-len=1 or 2            -   The number of additional DMRS symbols (DMRS-add-pos)                -   DMRS-add-pos=0, 1, 2, 3            -   Frequency hopping (FH) mode is set to one of the                followings                -   Mode1: intra-slot FH only                -   Mode2: inter-slot FH only        -   If the actual scheduling is smaller than the PDSCH or PUSCH            region, one of the proposed methods can be considered to            resolve the ambiguity about the additional DMRS.

Next, the second embodiment proposes another method for resolving theambiguity about the additional DMRS described above.

Second Embodiment

A method for determining the DMRS position described above according tothe actually scheduled DL or UL symbol length is provided in the presentdisclosure. In the second embodiment, the DMRS position for the PDSCH inthe downlink is set as follows.

DMRS position setting for PDSCH

-   -   PDSCH mapping type A        -   The position of the front-loaded DMRS is fixed at the 3rd or            4th symbol        -   For the position of the additional DMRS, refer to FIGS. 3A            to 3D    -   PDSCH mapping type B        -   The position of the front-loaded DMRS is the first scheduled            symbol        -   No additional DMRS for 2 or 4-symbol non-slot based            scheduling        -   For non-slot based scheduling of different symbol lengths            including 7-symbol non-slot based scheduling, refer to FIGS.            4A to 4C for the position of the additional DMRS

The DMRS position setting for the PDSCH can be divided according toPDSCH mapping types A and B. Specifically, PDSCH mapping type A can beinterpreted as a DMRS position setting scheme based on slot-basedscheduling, and PDSCH mapping type B can be interpreted as a DMRSposition setting scheme based on non-slot based scheduling. The positionof the front-loaded DMRS is set differently according to PDSCH mappingtype A or B. More specifically, in the case of PDSCH mapping type A, theposition of the front-loaded DMRS is fixed at the third or fourthsymbol. In the case of PDSCH mapping type B, the position of thefront-loaded DMRS is located at the first symbol of the scheduled PDSCH.For PDSCH mapping type A, the position of the front-loaded DMRS and theposition of the additional DMRS are shown together in FIGS. 3A to 3D.

In FIGS. 3A to 3D, the 300 portion indicates the position of a symbolthrough which the DMRS is transmitted and some of the subcarriers may beused for PDSCH transmission depending on the number of CDM groups used.The 310 b portion indicates a region where the PDSCH is scheduledaccording to the method proposed in the second embodiment. The 320portion indicates a region where the PDSCH is not transmitted. Forexample, the 320 portion can be used for the PUSCH region. In FIGS. 3Ato 3D, the 330 portion indicates a region where the PDCCH can betransmitted in the case of DL, and this portion can also be used forPDSCH transmission if the PDCCH is not transmitted.

With reference to FIGS. 3A to 3D, a description is given of the positionwhere the DMRS is transmitted based on the region where the PDSCH isactually scheduled according to the method proposed in the secondembodiment. In FIGS. 3A and 3B, c0 to c52 indicate possible DMRSpositions when the one-symbol front loaded DMRS is configured. In FIG.3D, c60 to c74 indicate possible DMRS positions when the two-symbolfront loaded DMRS is configured.

In FIG. 3A, c0 to c25 indicate possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured, c10to c15 indicate possible positions of the additional DMRS when the frontloaded DMRS is set at the 4th symbol, and c20 to c25 indicate possiblepositions of the additional DMRS when the front loaded DMRS is set atthe 3rd symbol. More specifically, in c10 and c20, the portion of theslot except for the last five symbols indicated in 320 is the regionwhere the PDSCH is scheduled, and the additional DMRS is transmitted viathe 8th symbol. In c11 and c21, the portion of the slot except for thelast four symbols indicated in 320 is the region where the PDSCH isscheduled, and the additional DMRS is transmitted via the 10th symbol.In c12 and c22, the portion of the slot except for the last threesymbols indicated in 320 is the region where the PDSCH is scheduled, andthe additional DMRS is transmitted via the 10th symbol. In c13 and c23,the portion of the slot except for the last two symbols indicated in 320is the region where the PDSCH is scheduled, and the additional DMRS istransmitted via the 10th symbol. In c14 and c24, the portion of the slotexcept for the last symbol indicated in 320 is the region where thePDSCH is scheduled, and the additional DMRS is transmitted via the 12thsymbol. In c15 and c25, the whole portion of the slot is the regionwhere the PDSCH is scheduled, and the additional DMRS is transmitted viathe 12th symbol.

In FIG. 3B, c30 to c44 indicate possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured,c30 to c34 indicate possible positions of the additional DMRS when thefront loaded DMRS is set at the 4th symbol, and c40 to c44 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the 3rd symbol. More specifically, in c30 and c40, the portion ofthe slot except for the last four symbols indicated in 320 is the regionwhere the PDSCH is scheduled, and the additional DMRS is transmitted viathe 7th and 10th symbols. In c31 and c41, the portion of the slot exceptfor the last three symbols indicated in 320 is the region where thePDSCH is scheduled, and the additional DMRS is transmitted via the 7thand 10th symbols. In c32 and c42, the portion of the slot except for thelast two symbols indicated in 320 is the region where the PDSCH isscheduled, and the additional DMRS is transmitted via the 7th and 10thsymbols. In c33 and c43, the portion of the slot except for the lastsymbol indicated in 320 is the region where the PDSCH is scheduled, andthe additional DMRS is transmitted via the 8th and 12th symbols. In c34and c44, the whole portion of the slot is the region where the PDSCH isscheduled, and the additional DMRS is transmitted via the 8th and 12thsymbols.

In FIG. 3C, c50 to c52 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.This is possible only when the front loaded DMRS is configured at the3rd symbol in consideration of the actual usage scenario as shown inFIG. 3C. More specifically, when three additional DMRSs are configuredas in c50 to c52, the additional DMRS is transmitted via the 6th, 9th,and 12th symbols regardless of the region where the PDSCH is scheduled.

In FIG. 3D, c60 to c74 indicate possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured.Considering the DMRS overhead and the actual usage scenario, at most oneadditional DMRS can be configured when the two-symbol front loaded DMRSis configured. In FIG. 3D, c60 to c64 indicate possible positions of theadditional DMRS when the first front loaded DMRS symbol is configured atthe 4th symbol. In FIG. 3D, c70 to c74 indicate possible positions ofthe additional DMRS when the first front loaded DMRS symbol isconfigured at the 3rd symbol. More specifically, in c60 and c70, theportion of the slot except for the last four symbols indicated in 320 isthe region where the PDSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c61 and c71, theportion of the slot except for the last three symbols indicated in 320is the region where the PDSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c62 and c72, theportion of the slot except for the last two symbols indicated in 320 isthe region where the PDSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c63 and c73, theportion of the slot except for the last symbol indicated in 320 is theregion where the PDSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 11th symbol. In c64 and c74, thewhole portion of the slot is the region where the PDSCH is scheduled,and the first symbol of the additional DMRS is transmitted via the 11thsymbol.

On the other hand, for PDSCH mapping type B, the position of thefront-loaded DMRS is set at the first scheduled symbol. In the case of 2or 4 symbol non-slot based scheduling, no additional DMRS is configuredowing to the short symbol length and DMRS overhead. For non-slot basedscheduling of different lengths including 7-symbol non-slot basedscheduling, a description is given of the position of the additionalDMRS with reference to FIGS. 4A to 4C. In FIGS. 4A and 4B, d10 to d32indicate possible DMRS positions when the one-symbol front loaded DMRSis configured. In FIG. 4C, d40 to d42 indicate possible DMRS positionswhen the two-symbol front loaded DMRS is configured.

In FIG. 4A, d10 to d13 indicate the possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured. Ind10, when the region where the PDSCH is scheduled is configured in the5th to 7th symbols, the additional DMRS is transmitted via the 5thsymbol. In d11, when the region where the PDSCH is scheduled isconfigured in the 8th and 9th symbols, the additional DMRS istransmitted via the 7th symbol. In d12, when the region where the PDSCHis scheduled is configured in the 10th and 11th symbols, the additionalDMRS is transmitted via the 9th symbol. In d13, when the region wherethe PDSCH is scheduled is configured in the 12th and 13th symbols, theadditional DMRS is transmitted via the 11th symbol.

In FIG. 4B, d20 to d22 indicate the possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured. Ind20, when the region where the PDSCH is scheduled is configured in the8th and 9th symbols, the additional DMRS is transmitted via the 4th and7th symbols. In d21, when the region where the PDSCH is scheduled isconfigured in the 10th and 11th symbols, the additional DMRS istransmitted via the 5th and 9th symbols. In d22, when the region wherethe PDSCH is scheduled is configured in the 12th and 13th symbols, theadditional DMRS is transmitted via the 6th and 11th symbols.

In FIG. 4B, d30 to d32 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.In this case, the additional DMRS is transmitted via the 4th, 7th, and10th symbols regardless of the region where the PDSCH is scheduled.

In FIG. 4C, d40 to d42 indicate the possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured. Ind40, when the region where the PDSCH is scheduled is configured in the8th and 9th symbols, the first symbol of the additional DMRS istransmitted via the 6th symbol. In d41, when the region where the PDSCHis scheduled is configured in the 10th and 11th symbols, the firstsymbol of the additional DMRS is transmitted via the 8th symbol. In d42,when the region where the PDSCH is scheduled is configured in the 12thand 13th symbols, the first symbol of the additional DMRS is transmittedvia the 10th symbol.

Based on the above description, for PDSCH mapping types A and B, theDMRS position can be set as follows according to the second embodiment.

For PDSCH, the reference point for l and the position l₀ of the firstDM-RS symbol depend on the mapping type:

-   -   for PDSCH mapping type A:        -   l is defined relative to the start of the slot        -   l₀=3 if the higher-layer parameter DL-DMRS-typeA-pos equals            3 and l₀=2 otherwise        -   PUSCH scheduling start point should be located earlier than        -   PUSCH scheduling ending point should be same or later than    -   for PDSCH mapping type B:        -   l is defined relative to the start of the scheduled PDSCH            resources        -   l₀=0

Table 9 shows the positions of the front-loaded and additional DMRSs forPDSCH mapping types A and B in the case of a single-symbol DMRS.

TABLE 9 PDSCH DMRS positions l⁻ for single-symbol DMRS Duration of DM-RSpositions l⁻ scheduled PDSCH mapping type A PDSCH mapping type B PDSCHDL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 3 0 1 2 3 ≤6 l₀ — — — l₀ 7 l₀ — — l₀ l₀, 4  8 l₀ — — — l₀ l₀, 6 l₀, 3, 6 —  9 l₀ l₀, 7 — — l₀l₀, 6 l₀, 3, 6 — 10 l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 11l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 12 l₀ l₀, 9 l₀, 6, 92, 5, l₀ l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 13 l₀ l₀, 11 l₀, 7, 11 2, 5,l₀ l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 14 l₀ l₀, 11 l₀, 7, 11 2, 5, l₀ 8,11

Table 10 shows the positions of the front-loaded and additional DMRSsfor PDSCH mapping types A and B in the case of a double-symbol DMRS.

TABLE 10 PDSCH DMRS positions l⁻ for double-symbol DMRS Duration ofDM-RS positions l⁻ scheduled PDSCH mapping type A PDSCH mapping type BPDSCH DL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 0 1 2 ≤8 l₀ — l₀  8l₀ — l₀ l₀, 5  9 l₀ — l₀ l₀, 5 10 l₀ l₀, 8 l₀ l₀, 7 11 l₀ l₀, 8 l₀ l₀, 712 l₀ l₀, 8 l₀ l₀, 9 13 l₀ l₀, 10 l₀ l₀, 9 14 l₀ l₀, 10 l₀

Table 11 shows the DMRS time index and possible antenna port numbers forthe single-symbol DMRS and double-symbol DMRS.

TABLE 11 PDSCH DMRS time index l′ and antenna ports p Single or doubleSupported antenna ports p symbol DM-RS l′ Configuration type 1Configuration type 2 single 0 1000-1003 1000-1005 double 0, 1 1000-10071000-1011

Based on the definition of the DMRS reference point l and the DMRSposition information l and l′ obtained from Tables 7, 8 and 9, the DMRSreference point for the PDSCH is set by l=l+l′.

Next, in the second embodiment, the DMRS position for the PUSCH (withouta hop) in the uplink can be set as follows.

DMRS position setting for PUSCH (without a hop)

-   -   PUSCH mapping type A        -   The position of the front-loaded DMRS is fixed at the 3rd or            4th symbol            -   Considering a common DMRS structure for DL and UL, if                fixed at the 3rd symbol for DL, it is also fixed at the                3rd symbol for UL, and if fixed at the 4th symbol for                DL, it is also fixed at the 4th symbol for UL        -   For the position of the additional DMRS, refer to FIGS. 3A            to 3D    -   PUSCH mapping type B        -   The position of the front-loaded DMRS is the first scheduled            symbol        -   No additional DMRS for 2 or 4 symbol non-slot based            scheduling        -   For non-slot based scheduling of different symbol lengths            including 7-symbol non-slot based scheduling, refer to FIGS.            4A to 4C for the position of the additional DMRS

The DMRS position setting for the PUSCH (without a hop) can be dividedaccording to PUSCH mapping types A and B. Specifically, PUSCH mappingtype A can be interpreted as a DMRS position setting scheme based onslot-based scheduling, and PUSCH mapping type B can be interpreted as aDMRS position setting scheme based on non-slot based scheduling. Theposition of the front-loaded DMRS is set differently according to PUSCHmapping type A or B. More specifically, in the case of PUSCH mappingtype A, the position of the front-loaded DMRS is fixed at the 3rd or 4thsymbol. In the case of PUSCH mapping type B, the position of thefront-loaded DMRS is located at the first symbol of the scheduled PDSCH.For PUSCH mapping type A, the position of the front-loaded DMRS and theposition of the additional DMRS may be given together as shown in FIGS.3A to 3D.

In FIGS. 3A to 3D, the 300 portion indicates the position of a symbolthrough which the DMRS is transmitted and some of the subcarriers may beused for PUSCH transmission depending on the number of CDM groups used.The 310 b portion indicates the region where the PUSCH is scheduledaccording to the method proposed in the second embodiment. The 320portion indicates a region where the PUSCH is not transmitted. Forexample, the 320 portion can be used for SRS transmission and a shortPUCCH region. The 330 portion indicates a region where the PDCCH can betransmitted in the case of DL, and this portion can also be used forPUSCH transmission in the case of UL.

With reference to FIGS. 3A to 3D, a description is given of the positionwhere the DMRS is transmitted based on the region where the PUSCH isscheduled according to the method proposed in the second embodiment ofthe present invention. In FIG. 3A, c10 to c25 indicate possible DMRSpositions when the one-symbol front loaded DMRS is configured. In FIG.3D, c60 to c74 indicate possible DMRS positions when the two-symbolfront loaded DMRS is configured.

In FIG. 3A, c10 to c25 indicate possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured, c10to c15 indicate possible positions of the additional DMRS when the frontloaded DMRS is set at the 4th symbol, and c20 to c25 indicate possiblepositions of the additional DMRS when the front loaded DMRS is set atthe 3rd symbol. More specifically, in c10 and c20, the portion of theslot except for the last five symbols indicated in 320 is the regionwhere the PUSCH is scheduled, and the additional DMRS is transmitted viathe 8th symbol. In c11 and c21, the portion of the slot except for thelast four symbols indicated in 320 is the region where the PUSCH isscheduled, and the additional DMRS is transmitted via the 10th symbol.In c12 and c22, the portion of the slot except for the last threesymbols indicated in 320 is the region where the PUSCH is scheduled, andthe additional DMRS is transmitted via the 10th symbol. In c13 and c23,the portion of the slot except for the last two symbols indicated in 320is the region where the PUSCH is scheduled, and the additional DMRS istransmitted via the 10th symbol. In c14 and c24, the portion of the slotexcept for the last symbol indicated in 320 is the region where thePUSCH is scheduled, and the additional DMRS is transmitted via the 12thsymbol. In c15 and c25, the whole portion of the slot is the regionwhere the PUSCH is scheduled, and the additional DMRS is transmitted viathe 12th symbol.

In FIG. 3B, c30 to c44 indicate possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured,c30 to c34 indicate possible positions of the additional DMRS when thefront loaded DMRS is set at the 4th symbol, and c40 to c44 indicatepossible positions of the additional DMRS when the front loaded DMRS isset at the 3rd symbol. More specifically, in c30 and c40, the portion ofthe slot except for the last four symbols indicated in 320 is the regionwhere the PUSCH is scheduled, and the additional DMRS is transmitted viathe 7th and 10th symbols. In c31 and c41, the portion of the slot exceptfor the last three symbols indicated in 320 is the region where thePUSCH is scheduled, and the additional DMRS is transmitted via the 7thand 10th symbols. In c32 and c42, the portion of the slot except for thelast two symbols indicated in 320 is the region where the PUSCH isscheduled, and the additional DMRS is transmitted via the 7th and 10thsymbols. In c33 and c43, the portion of the slot except for the lastsymbol indicated in 320 is the region where the PUSCH is scheduled, andthe additional DMRS is transmitted via the 8th and 12th symbols. In c34and c44, the whole portion of the slot is the region where the PUSCH isscheduled, and the additional DMRS is transmitted via the 8th and 12thsymbols.

In FIG. 3C, c50 to c52 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.This is possible only when the front loaded DMRS is configured at the3rd symbol in consideration of the actual usage scenario as shown inFIG. 3C. More specifically, when three additional DMRSs are configuredas in c50 to c52, the additional DMRS is transmitted via the 6th, 9th,and 12th symbols regardless of the region where the PUSCH is scheduled.

In FIG. 3D, c60 to c74 indicate possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured.Considering the DMRS overhead and the actual usage scenario, at most oneadditional DMRS can be configured when the two-symbol front loaded DMRSis configured. In FIG. 3D, c60 to c64 indicate possible positions of theadditional DMRS when the first front loaded DMRS symbol is configured atthe 4th symbol. In FIG. 3D, c70 to c74 indicate possible positions ofthe additional DMRS when the first front loaded DMRS symbol isconfigured at the 3rd symbol. More specifically, in c60 and c70, theportion of the slot except for the last four symbols indicated in 320 isthe region where the PUSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c61 and c71, theportion of the slot except for the last three symbols indicated in 320is the region where the PUSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c62 and c72, theportion of the slot except for the last two symbols indicated in 320 isthe region where the PUSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 9th symbol. In c63 and c73, theportion of the slot except for the last symbol indicated in 320 is theregion where the PUSCH is scheduled, and the first symbol of theadditional DMRS is transmitted via the 11th symbol. In c64 and c74, thewhole portion of the slot is the region where the PUSCH is scheduled,and the first symbol of the additional DMRS is transmitted via the 11thsymbol.

On the other hand, for PUSCH mapping type B, the position of thefront-loaded DMRS is set at the first scheduled symbol. In the case of 2or 4 symbol non-slot based scheduling, no additional DMRS is configuredowing to the short symbol length and DMRS overhead. For non-slot basedscheduling of different lengths including 7-symbol non-slot basedscheduling, a description is given of the position of the additionalDMRS with reference to FIGS. 4A to 4C. In FIGS. 4A and 4B, d10 to d32indicate possible DMRS positions when the one-symbol front loaded DMRSis configured. In FIG. 4C, d40 to d42 indicate possible DMRS positionswhen the two-symbol front loaded DMRS is configured.

In FIG. 4A, d10 to d13 indicate the possible DMRS positions when theone-symbol front loaded DMRS and one additional DMRS are configured. Ind10, when the region where the PUSCH is scheduled is configured in the5th to 7th symbols, the additional DMRS is transmitted via the 5thsymbol. In d11, when the region where the PUSCH is scheduled isconfigured in the 8th and 9th symbols, the additional DMRS istransmitted via the 7th symbol. In d12, when the region where the PUSCHis scheduled is configured in the 10th and 11th symbols, the additionalDMRS is transmitted via the 9th symbol. In d13, when the region wherethe PUSCH is scheduled is configured in the 12th and 13th symbols, theadditional DMRS is transmitted via the 11th symbol.

In FIG. 4B, d20 to d22 indicate the possible DMRS positions when theone-symbol front loaded DMRS and two additional DMRSs are configured. Ind20, when the region where the PUSCH is scheduled is configured in the8th and 9th symbols, the additional DMRS is transmitted via the 4th and7th symbols. In d21, when the region where the PUSCH is scheduled isconfigured in the 10th and 11th symbols, the additional DMRS istransmitted via the 5th and 9th symbols. In d22, when the region wherethe PUSCH is scheduled is configured in the 12th and 13th symbols, theadditional DMRS is transmitted via the 6th and 11th symbols.

In FIG. 4B, d30 to d32 indicate possible DMRS positions when theone-symbol front loaded DMRS and three additional DMRSs are configured.In this case, the additional DMRS is transmitted via the 4th, 7th, and10th symbols regardless of the region where the PUSCH is scheduled.

In FIG. 4C, d40 to d42 indicate the possible DMRS positions when thetwo-symbol front loaded DMRS and one additional DMRS are configured. Ind40, when the region where the PUSCH is scheduled is configured in the8th and 9th symbols, the first symbol of the additional DMRS istransmitted via the 6th symbol. In d41, when the region where the PUSCHis scheduled is configured in the 10th and 11th symbols, the firstsymbol of the additional DMRS is transmitted via the 8th symbol. In d42,when the region where the PUSCH is scheduled is configured in the 12thand 13th symbols, the first symbol of the additional DMRS is transmittedvia the 10th symbol.

Based on the above description, for PUSCH mapping types A and B, theDMRS position can be set as follows according to the second embodiment.

For PUSCH, the reference point for l and the position l₀ of the firstDM-RS symbol depend on the mapping type:

-   -   for PUSCH mapping type A:        -   l is defined relative to the start of the slot        -   l₀=3 if the higher-layer parameter DL-DMRS-typeA-pos equals            3 and l₀=2 otherwise        -   PUSCH scheduling start point should be located earlier than            l₀        -   PUSCH scheduling ending point should be same or later than            l₀    -   for PUSCH mapping type B:        -   l is defined relative to the start of the scheduled PUSCH            resources        -   l₀=0

Table 12 shows the positions of the front-loaded and additional DMRSsfor PUSCH mapping types A and B in the case of a single-symbol DMRS.

TABLE 12 PUSCH DMRS positions l⁻ for single-symbol DMRS Duration ofDM-RS positions l⁻ scheduled PUSCH mapping type A PUSCH mapping type BPDSCH DL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 3 0 1 2 3 ≤7 l₀ — —— l₀ l₀, 4 — —  8 l₀ — — — l₀ l₀, 6 l₀, 3, 6 —  9 l₀ l₀, 7 — — l₀ l₀, 6l₀, 3, 6 — 10 l₀ l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 11 l₀l₀, 9 l₀, 6, 9 — l₀ l₀, 8 l₀, 4, 8 l₀, 3, 6, 9 12 l₀ l₀, 9 l₀, 6, 9 2,5, l₀ l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 13 l₀ l₀, 11 l₀, 7, 11 2, 5, l₀l₀, 10 l₀, 5, 10 l₀, 3, 8, 11 6, 9 14 l₀ l₀, 11 l₀, 7, 11 2, 5, — — — —8, 11

Table 13 shows the positions of the front-loaded and additional DMRSsfor PUSCH mapping types A and B in the case of a double-symbol DMRS.

TABLE 13 PUSCH DMRS positions l⁻ for double-symbol DMRS Duration ofDM-RS positions l⁻ scheduled PUSCH mapping type A PUSCH mapping type BPDSCH DL-DMRS-add-pos DL-DMRS-add-pos symbols 0 1 2 3 0 1 2 3 ≤7 l₀ — l₀—  8 l₀ — l₀ l₀, 5  9 l₀ — l₀ l₀, 5 10 l₀ l₀, 8 l₀ l₀, 7 11 l₀ l₀, 8 l₀l₀, 7 12 l₀ l₀, 8 l₀ l₀, 9 13 l₀ l₀, 10 l₀ l₀, 9 14 l₀ l₀, 10 — —

Table 14 shows the DMRS time index and possible antenna port numbers forthe single-symbol DMRS and double-symbol DMRS.

TABLE 14 PUSCH DMRS time index l' and antenna ports p Supported antennaports p DM-RS duration l′ Configuration type 1 Configuration type 2single-symbol 0 1000-1003 1000-1005 DM-RS double-symbol 0, 1 1000-10071000-1011 DM-RS

Based on the definition of the DMRS reference point l and the DMRSposition information l and l′ obtained from Tables 10, 11 and 12, theDMRS reference point for the PDSCH is set by l=l+l′.

Hereinabove, a description is given of the DMRS position setting methodfor the PUSCH (without a hop). Next, for the PUSCH (with a hop), theDMRS position can be set as follows.

DMRS position setting for PUSCH (with a hop)

-   -   First hop        -   PUSCH mapping type A            -   The position of the one-symbol front loaded DMRS is                fixed at the 3rd or 4th symbol            -   If 5 or more symbols are scheduled relative to the                front-loaded DMRS, the position of the additional DMRS                is at the 5th symbol relative to the front-loaded DMRS.                Otherwise, no additional DMRS is used        -   PUSCH mapping type B            -   The position of the front-loaded DMRS is the first                scheduled symbol            -   If 5 or more symbols are scheduled relative to the                front-loaded DMRS, the position of the additional DMRS                is at the 5th symbol relative to the front-loaded DMRS.                Otherwise, no additional DMRS is used    -   Second hop        -   The position of the front-loaded DMRS is at the first symbol            of the PUSCH corresponding to the second hop        -   If 5 or more symbols are scheduled relative to the            front-loaded DMRS corresponding to the second hop, the            position of the additional DMRS is at the 5th symbol            relative to the front-loaded DMRS. Otherwise, no additional            DMRS is used    -   The same DMRS position is configured for both CP-OFDM and        DFT-S-OFDM

In the second embodiment, the DMRS position setting is determinedaccording to the actually scheduled DL or UL symbol length. The DMRSinformation can be configured as follows. In the NR system, theDMRS-related information can be identified through the PBCH, RRC, groupcommon DCI, and UE-specific DCI, and each signaling may include thefollowing information.

-   -   When the position of the front-loaded DMRS is fixed at the 3rd        or 4th symbol through the PBCH, receive an indication of whether        the front-loaded DMRS is located at the 3rd symbol or at the 4th        symbol    -   Slot format indication (SFI) information can be configured via        cell-specific RRC, and the SFI information is notified via        system information (SIB2)    -   The SFI information may be configured and notified via        UE-specific RRC    -   The SFI information may be dynamically configured and notified        via group common DCI    -   Some or all of the following information may be configured and        received via UE specific DCI        -   Information about PDSCH mapping types A and B or PUSCH            mapping types A and B            -   Indication of mapping type A or B        -   PDSCH or PUSCH scheduling information            -   Start position and duration of PDSCH or PUSCH        -   Indication of DMRS port information            -   Scheduled DMRS port information            -   Number of CDM groups scheduled together for PDSCH rate                matching            -   Indication of whether front-loaded DMRS is one-symbol                DMRS or two-symbol DMRS        -   Frequency hopping enabling or disabling    -   Prior to RRC setup, the DMRS configuration for PDSCH or PUSCH is        subdivided as follows according to the configured SFI        information and DCI scheduling information        -   DMRS pattern is assumed to be DMRS-config-type 1        -   In the case of slot-based scheduling, a one-symbol            front-loaded DMRS and two additional DMRSs are configured by            default, and for their positions, refer to PDSCH mapping            type A in Table 9 (for PDSCH DMRS) and PUSCH mapping type A            in Table 12 (for PUSCH DMRS).        -   In the case of 2 or 4-symbol non-slot-based scheduling, only            the one-symbol front-loaded DMRS is configured and no            additional DMRS is configured.        -   In the case of non-slot based scheduling of different symbol            lengths including 7-symbol non-slot based scheduling, a            single-symbol front-loaded DMRS and one single-symbol            additional DMRS are configured; for their positions, refer            to PDSCH mapping type B in Table 9 (for PDSCH DMRS) and            PUSCH mapping type B in Table 12 (for PUSCH DMRS).        -   In the case of PUSCH (with a hop), Mode 1 (intra-slot FH            only) is assumed when frequency hopping is enabled by the            DCI, and no additional DMRS is configured for PUSCH mapping            type A and the additional DMRS is configured by default for            PUSCH mapping type B.    -   Prior to RRC setup, PDSCH DMRS transmission is allowed only for        SU-MIMO with DMRS port 0, and FDM between the PDSCH symbol and        the DMRS symbol is not allowed for slot-based scheduling and 4        or 7-symbol non-slot-based scheduling. However, FDM between the        PDSCH symbol and the DMRS symbol is allowed for 2-symbol        non-slot-based scheduling.    -   Prior to RRC setup, PUSCH DMRS transmission is allowed only for        SU-MIMO with DMRS port 0, and FDM between the PDSCH symbol and        the DMRS symbol is not allowed.    -   After RRC setup, the DMRS configuration for PDSCH or PUSCH is        subdivided as follows according to the DMRS information        configured via RRC, configured SFI information, and DCI        scheduling information DMRS information configured via RRC        -   DMRS configuration type (DMRS-config-type)            -   DMRS-config-type=1 or 2                -   The maximum number of the front-loaded DMRS symbols                    (DMRS-max-len)                -   DMRS-max-len=1 or 2            -   The number of additional DMRS symbols (DMRS-add-pos)                -   DMRS-add-pos=0, 1, 2, 3            -   Frequency hopping (FH) mode is set to one of the                following:                -   Mode1: intra-slot FH only                -   Mode2: inter-slot FH only        -   The DMRS position is determined based on the scheduling            information interpreted using the DCI and the number of            additional DMRSs set by RRC            -   For PDSCH, refer to Tables 9 and 10            -   For PUSCH (without a hop), refer to Tables 12 and 13            -   For PUSCH (with a hop), refer to DMRS position setting                for PUSCH (with a hop)

In the second embodiment, the DMRS information configuration isdetermined according to the actually scheduled UL or UL symbol length;and, unlike the method of the first embodiment, no ambiguity about theadditional DMRS occurs even when the scheduled region is smaller thanthe PDSCH or PUSCH region. In addition, the method of the secondembodiment can be used for DMRS position setting for the extended cyclicprefix (ECP). When the same DMRS configuration is used for the normalcyclic prefix (NCP) and the ECP, if the DMRS position setting method ofthe second embodiment is used based on the actually scheduled UL or ULsymbol length, no ambiguity occurs. Specifically, one slot is composedof 14 symbols for the NCP, and one slot is composed of 12 symbols forthe ECP. In the second embodiment where the DMRS position is determinedaccording to the symbol length of the actually scheduled PDSCH or PUSCH,the DMRS position setting is described based on the NCP, but the samecan be applied to the case of the ECP. For example, in FIG. 3A, amongthe cases indicated by c10 to c25, the cases indicated by c10 to c13 andc20 to c23 can be used for configuring the DMRS information for the ECPwhere the slot includes 12 symbols.

Third Embodiment

A method for configuring the DMRS information via RRC is provided in thepresent disclosure. Specifically, DMRS configuration parameters may varydepending on slot based scheduling or non-slot based scheduling. Forexample, in slot based scheduling, because the scheduled symbol lengthfor the PDSCH or PUSCH can be up to 14 symbols, it is possible toconfigure the double-symbol DMRS. However, in non-slot based scheduling,it is inappropriate to configure a double-symbol DMRS when the scheduledsymbol length for the PDSCH or PUSCH is 2.

FIG. 5 is a diagram of a method for setting the number of front-loadedDMRS symbols based on the number of scheduled data symbols, according toan embodiment. As shown in FIG. 5, it is possible to set the maximumnumber of front-loaded DMRS symbols (DMRS-max-len), which can be set viaRRC, according to the number of scheduled PDSCH or PUSCH OFDM symbols.In FIG. 5, at step 500, the threshold for the number of scheduled PDSCHor PUSCH OFDM symbols is set to 4. If the number of scheduled PDSCH orPUSCH OFDM symbols is less than or equal to 4, DMRS-max-len that can beset in RRC is set to 1 at step 520. If the number of scheduled PDSCH orPUSCH OFDM symbols is greater than 4, DMRS-max-len that can be set inRRC is set to {1, 2} at step 510. The threshold may be set to a valueother than 4, but here the threshold value is proposed to be 4 inconsideration of the scheduled symbol length and the DMRS overhead. Inaddition, DMRS patterns can be set independently for slot basedscheduling and non-slot based scheduling. However, whereas the DMRSpattern configuration is set semi-statically to one of the two types(DMRS-config-type 1 or 2) through RRC, slot based scheduling or non-slotbased scheduling is dynamically determined through DCI. Hence, it may bedesirable to fix the DMRS patterns set in RRC according to slot-basedscheduling or non-slot based scheduling. It may be possible to place arestriction on the RRC DMRS pattern setting so that if the DMRS patternfor slot-based scheduling is set to DMRS-config-type 1 in RRC, the DMRSpattern for non-slot based scheduling is also set to DMRS-config-type 1.

The following tables illustrate specific methods for setting the RRCDMRS information according to the scheduling schemes. According to theabove-described third embodiment, the DMRS-related configuration can beset separately in RRC according to slot-based scheduling and non-slotbased scheduling. In the RRC notation, the downlink and the uplink canbe expressed as PDSCH mapping type A or PUSCH mapping type A forslot-based scheduling and as PDSCH mapping type B or PUSCH mapping typeB for non-slot based scheduling. The terms for the RRC DMRSconfiguration information described in the following tables are definedin consideration of their functions in the present disclosure and shouldbe construed in accordance with the spirit of the present disclosure.Table 15 below shows an example in which the DMRS-related configurationis separately described in RRC according to slot-based scheduling ornon-slot based scheduling.

TABLE 15 -- ASN1START DMRS-Info-slot  CHOICE{  DMRS-config-type INTEGER(1, 2) ,  DMRS-max-len INTEGER (1, 2) ,  DMRS-add-num INTEGER (0, 1, 2,3) , } DMRS-Info-Nonslot  CHOICE{  DMRS-config-type INTEGER (1, 2) , DMRS-max-len-2-4-sym INTEGER (1) ,  DMRS-max-len-7-sym INTEGER (1, 2) , DMRS-add-num-2-4-sym INTEGER (0) ,  DMRS-add-num-7-sym INTEGER (0, 1) ,} -- ASN1STOP

In Table 15, DMRS-config-type indicates the setting value for the DMRSpattern and can be restricted to have the same value for slot-basedscheduling and non-slot based scheduling as described above.DMRS-max-len indicates the maximum number of front-loaded DMRS symbolsand may be set to 1 or 2 for slot based scheduling. For non-slot basedscheduling, DMRS-max-len may have a restriction on the value accordingto the scheduled symbol length as shown in Table 13. DMRS-add-numindicates the number of additional DMRSs and can be set differentlyaccording to slot-based scheduling and non-slot based scheduling. Inparticular, for non-slot based scheduling, DMRS-add-num may be set toone of different values depending on the number of scheduled symbols asshown in Table 15. Table 16 below shows an example in which theDMRS-related configuration is separately described in RRC according toslot-based scheduling, non-slot based scheduling, and the symbol length.The terms and settings for the DMRS configuration information in Table16 are interpreted similarly to those in Table 15.

TABLE 16 -- ASN1START DMRS-Info-slot CHOICE{  DMRS-config-type INTEGER(1, 2) ,  DMRS-max-len INTEGER (1, 2) ,  DMRS-add-num INTEGER (0, 1, 2,3) , } DMRS Info-Nonslot-2-4-sym CHOICE{  DMRS-config-type INTEGER (1,2) ,  DMRS-max-len INTEGER (1) ,  DMRS add-num INTEGER (0) , }DMRS-Info-Nonslot-7-sym CHOICE{  DMRS-config-type INTEGER (1, 2) , DMRS-max-len INTEGER (1, 2) ,  DMRS-add-num INTEGER (0, 1) , } --ASN1STOP

Table 17 below shows an example in which the DMRS-related configurationis set in RRC as a group for slot-based scheduling and non-slot basedscheduling, but detailed information is set separately for slot-basedscheduling and non-slot based scheduling. The terms and settings for theDMRS configuration information in Table 17 are interpreted similarly tothose in Table 15.

TABLE 17 -- ASN1START DMRS-Info CHOICE {  DMRS-config-type INTEGER (1,2) ,  DMS-max-len-slot INTEGER (1, 2) ,  DMRS-add-num-slot INTEGER (0,1, 2, 3) ,  DMRS-max-len-2-4-sym INTEGER (1) ,  DMRS-max-len-7-symINTEGER(1, 2) ,  DMRS-add-num-2-4-sym INTEGER (0) ,  DMRS-add-num-7-symINTEGER(0,1) , } -- ASN1STOPFor ease of description, the settings in Tables 15, 16, and 17 are notsubdivided for DL and UL. However, as described above, the settings inTables 15, 16, and 17 can be separately given for DL and UL.

Fourth Embodiment

Although the number of bits required for DMRS port indication may varyaccording to the DMRS configuration, the fourth embodiment proposes amethod of composing a DMRS port indication table to maintain the sameDCI overhead. Specifically, for the DMRS port indication, the followinginformation can be included in the DMRS port indication table.

-   -   Information about scheduled DMRS ports    -   Number of CDM groups for rate matching    -   Information about whether the DMRS pattern is a single-symbol        DMRS or a double-symbol DMRS

The number of bits needed to indicate the above information items may bechanged according to the DMRS information settings. For example, asdescribed in the third embodiment, in the case of non-slot basedscheduling, it is inappropriate to configure a double-symbol DMRS whenthe scheduled PDSCH or PUSCH symbol length is 2. Hence, when thescheduled PDSCH or PUSCH symbol length is 2 or 4, as in the methodproposed in the third embodiment, it is possible to restrict the maximumnumber of front-loaded DMRS symbols (DMRS-max-len) that can be set inRRC to take a value of 1. If DMRS-max-len is set to 2, whether theactual number of front-loaded DMRS symbols is 1 or 2 can be indicatedvia the DCI and the DMRS port indication table. Hence, when DMRS-max-lenis set to 2, the number of bits for the DMRS port indication can beincreased. More generally, the number of bits of the DMRS portindication table is determined by the DMRS pattern (DMRS-config-type 1or 2) or the maximum number of front-loaded DMRS symbols (DMRS-max-len)set in RRC. Because DMRS-config-type 1 as a DMRS pattern supports up to8 orthogonal DMRS ports and DMRS-config-type 2 supports up to 12orthogonal DMRS ports, DMRS-config-type 2 requires more bits to indicatethe DMRS ports than DMRS-config-type 1. Therefore, as suggested in thethird embodiment, the DMRS information may be differently set in RRC forslot-based scheduling and non-slot based scheduling; and, accordingly,the number of required bits for the DMRS port indication table may bechanged. As described in the third embodiment, slot-based scheduling maybe interpreted as PDSCH mapping type A or PUSCH mapping type A, andnon-slot based scheduling may be interpreted as PDSCH mapping type B orPUSCH mapping type B. Hence, the DMRS information configuration and thecorresponding number of DMRS port indication bits may be differentaccording to PDSCH mapping type, PUSCH mapping type, slot-basedscheduling, and non-slot based scheduling. In this case, the followingmethod can be used to make the number of DCI bits equal.

Because the scheduled DMRS port information and the number of CDM groupsfor rate matching are different according to the DMRS pattern, themethod for making the number of DCI bits equal may first be subdividedaccording to the DMRS pattern.

Composing the DMRS port indication table when the DMRS pattern is set toDMRS-config-type 1.

-   -   Method 1: assuming that DMRS-max-len is set to 2, compose a DMRS        port indication table with the required number of bits, and add        zero padding bits to match the number of bits of the DMRS port        indication table for DMRS-config-type=2 and DMRS-max-len=2    -   Method 2: compose each DMRS port indication table with the        required number of bits for DMRS-max-len=1 and 2, and add zero        padding bits to match the number of bits of the DMRS port        indication table for DMRS-config-type=2 and DMRS-max-len=2

When the DMRS pattern is set to DMRS-config-type 1, in method 1, a DMRSport indication table is composed by assuming that DMRS-max-len is 2,and zero padding bits are added to match the DCI overhead of the casefor DMRS-config-type=2 and DMRS-max-len=2 where the maximum number ofbits is required for table composition. In method 1, if DMRS-max-len=1,the information corresponding to the double-symbol DMRS in the DMRS portindication table is not utilized.

On the other hand, in method 2, each DMRS port indication table iscomposed for configured DMRS-max-len, and zero padding bits are added tomatch the DCI overhead of the case for DMRS-config-type=2 andDMRS-max-len=2 where the maximum number of bits is required for tablecomposition.

Composing the DMRS port indication table when the DMRS pattern is set toDMRS-config-type 2.

-   -   Method 1: assuming that DMRS-max-len is set to 2, compose a DMRS        port indication table with the required number of bits. There is        no need to add zero padding bits.    -   Method 2: compose each DMRS port indication table with the        required number of bits for DMRS-max-len=1 and 2, and add zero        padding bits to match the number of bits of the DMRS port        indication table for DMRS-config-type=2 and DMRS-max-len=2

When the DMRS pattern is set to DMRS-config-type 2, in method 1, a DMRSport indication table is composed by assuming that DMRS-max-len is 2,and there is no need to add zero padding bits to match the DCI overheadbecause this case requires the maximum number of bits for tablecomposition. In method 1, if DMRS-max-len=1, the informationcorresponding to the double-symbol DMRS in the DMRS port indicationtable is not utilized. On the other hand, in method 2, each DMRS portindication table is composed for configured DMRS-max-len, and zeropadding bits are added to match the DCI overhead of the case forDMRS-config-type=2 and DMRS-max-len=2 where the maximum number of bitsis required for table composition. In summary, although the number ofbits required for DMRS port indication may vary depending on the DMRSconfiguration values, it is possible to prevent additional blinddetection because of a change in the DCI format size when using themethod of the fourth embodiment as a method for keeping the DCI overheadthe same.

Fifth Embodiment

The present disclosure provides a method for determining the length of aDL or UL DMRS sequence for CP-OFDM in the NR system.

FIG. 6 is a diagram of generation of a DMRS sequence, according tovarious embodiments of the present invention. In FIG. 6, the signal isgenerated as a pseudo-random (PN) sequence based on a Gold sequence oflength 31.

More specifically, as shown in FIG. 6, the first m-sequence x₁(n)generated from the polynomial D³¹+D³+1 of the upper register and thesecond m-sequence x₂(n) generated from the polynomial D³¹+D³+D²+D+1 ofthe lower register are combined to generate the PN sequence C(n). Thiscan be represented by Equation (1) below.

c(n)=(x ₁(n+N _(C))+x ₂(n+N _(C)))mod 2

x ₁(n+31)=(x ₁(n+3)+x ₁(n))mod 2

x ₂(n+31)=(x ₂(n+3)+x ₂(n+2)+x ₂(n+1)+x ₂(n))mod 2  (1)

Here, N_(c)=1600 and register initialization is performed as follows.

-   -   The first m-sequence x₁(n) generated by the upper register is        initialized to a fixed pattern x₁(0)=1, x₁(n)=0, n=1, 2, 3, . .        . , 30.    -   The second m-sequence x₂(n) generated by the lower register is        initialized with Equation (2) according to the scrambling        condition required by each signal.

c _(init)=Σ_(i=0) ³⁰ x ₂(i)·2^(i)  (2)

More specifically, in the case of NR DMRS, Equation (2) is representedby Equation (3) below.

c _(init)=(2¹⁷(14n _(s) +l+1)(2N _(ID) ^(n) ^(SCID) +1)+2N _(ID) ^(n)^(SCID) +n _(SCID))mod 2³¹  (3)

In Equation (3), l denotes the OFDM symbol index in a slot and n_(s)denotes the slot index. Also, ●n_(SCID)∈{0, 1} and N_(ID) ^(N) ^(SCID)∈{0, 1, . . . , 65535} are given by the higher-layer parameterUL-DMRS-Scrambling-ID if provided

-   -   n_(SCID)=0 and N_(ID) ^(N) ^(SCID) =N_(ID) ^(cell) otherwise

As described above, in the case of the DMRS, initialization is performedfor every DMRS symbol. For DL CP-OFDM, the reference signal fortransmitting the DMRS port is represented by Equation (4) below.

$\begin{matrix}{{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},} & (4)\end{matrix}$

Here, for DL CP-OFDM, m is given by Equation (5) below, which depends onwhether the PDSCH carries the remaining minimum system information(RMSI).

$\begin{matrix}{m = \left\{ \begin{matrix}{0,1,\ldots\;,{{A \cdot N_{RB}^{initial}} - 1}} & {{for}\mspace{14mu}{PDSCH}\mspace{14mu}{transmission}\mspace{14mu}{carring}\mspace{14mu}{RMSI}} \\{0,1,\ldots\;,{{A \cdot N_{CRB}^{\max}} - 1}} & {\mspace{329mu}{otherwise}}\end{matrix} \right.} & (5)\end{matrix}$

Here, N_(RB) ^(initial) indicates the number of RBs corresponding to theinitial active bandwidth part for the PDSCH carrying the RMRI, and thiscan be interpreted as the number of RBs corresponding to the bandwidthof the control resource set (CORESET) configured in the PBCH. N_(CRB)^(max) indicates the maximum number of RBs of the common resource blocksin the case of the PDSCH not carrying the RMRI and is 275 RBs in the NRsystem. The value of A can be set to 12 regardless of the DMRS patternwhen generating different sequences for all DMRS antenna ports. When asequence is generated based on one antenna port and the DMRS sequence isshared between different antenna ports, the value of A may be changedaccording to the DMRS pattern. More specifically, the DMRS sequence isinitialized based on one symbol. With reference to the single-symbolDMRS of FIG. 2, for DMRS-config-type=1, one antenna port belongs to oneCDM group, which occupies six REs in one RB, and the value of A can beset to 6 (A=6). For DMRS-config-type=2, one antenna port belongs to oneCDM group, which occupies four REs in one RB, and the value of A can beset to 4 (A=4). On the other hand, in the case of UL CP-OFDM, m is givenby Equation (6) below.

m=0,1, . . . ,A·N _(CRB) ^(max)−1  (6)

Here, N_(CRB) ^(max) indicates the maximum number of RBs of the commonresource blocks and is 275 RBs in the NR system.

Sixth Embodiment

The sixth embodiment proposes a method for determining the position ofthe start symbol for the DMRS position and scheduling. Specifically, asdescribed in the first and second embodiments, whether PDSCH mappingtype A or B is used is signaled to the terminal through the DCI. ForPDSCH mapping types A and B, it is agreed that the start symbol andduration of the scheduled resources are signaled through UE-specificDCI. However, for PDSCH mapping type A, the first DMRS position is thethird or fourth symbol, and whether the position of the first DMRSsymbol is the third symbol or the fourth symbol is signaled through thesystem information transmitted via the PBCH. Hence, when scheduling isperformed for PDSCH mapping type A, there is a problem that the startsymbol must be located at least before the third or fourth symbol.

Three methods for solving this problem are described below.

In the first method, when the start symbol and duration for scheduling,and the signaling table and/or equation are separately specified forPDSCH mapping types A and B, settings for the signaling table and/orequation may be used. For example, if the start symbol and durationinformation used for scheduling and the corresponding signaling tableand/or equation settings are separately specified for PDSCH mappingtypes A and B, the signaling table and/or equation settings can be usedto solve the above problem.

Specifically, for the terminal having received a setting for PDSCHmapping type A via the DCI, if the first DMRS position set via the PBCHis the third symbol, the signaling table and/or equation for PDSCHmapping type A is configured so that the start symbol for PDSCHscheduling is not set after the fourth symbol.

For the terminal having received a setting for PDSCH mapping type A viathe DCI, if the first DMRS position set via the PBCH is the fourthsymbol, the signaling table and/or equation for PDSCH mapping type A isconfigured so that the start symbol for PDSCH scheduling is not setafter the fifth symbol.

In the second method, when the start symbol and duration for scheduling,and the signaling table and/or equation are not separately specified forPDSCH mapping types A and B, it may be determined that the terminal isin a wrong state. For example, when the start symbol and durationinformation used for scheduling and the corresponding signaling tableand/or equation settings are not separately specified for PDSCH mappingtypes A and B, if the above problem occurs, it may be determined thatthe terminal is in a wrong state.

Specifically, for a terminal having received a setting for PDSCH mappingtype A via the DCI, if the first DMRS position set via the PBCH is thethird symbol, the terminal does not expect the start symbol for PDSCHscheduling to be set after the fourth symbol.

For a terminal having received a setting for PDSCH mapping type A viathe DCI, if the first DMRS position set via the PBCH is the fourthsymbol, the terminal does not expect the start symbol for PDSCHscheduling to be set after the fifth symbol.

In the third method, the first DMRS position for PDSCH mapping type Acan be changed. Specifically, for the terminal having received a settingfor PDSCH mapping type A via the DCI, when the first DMRS position setvia the PBCH is the third symbol, if the start symbol for PDSCHscheduling is set after the fourth symbol, the first DMRS position islocated at the first scheduled symbol. For the terminal having receiveda setting for PDSCH mapping type A via the DCI, when the first DMRSposition set via the PBCH is the fourth symbol, if the start symbol forPDSCH scheduling is set after the fifth symbol, the first DMRS positionis located at the first scheduled symbol.

Although the settings for the table and/or equation are signaled throughthe UE-specific DCI in the above description, they may also be signaledto the terminal via RRC signaling or a MAC CE.

In the first method, settings for the signaling table and/or equationare separately specified for PDSCH mapping types A and B. The aboveproblem can be solved through setting a signaling table and/or equation,but the signaling can become too complicated. The second method maysolve the problem of the first method by causing the terminal todetermine the described specific case as a wrong operation. In the thirdmethod, the first DMRS position is changed and hence an additional DMRSposition may be set, increasing the implementation complexity of theterminal.

The terminal and the base station are shown in FIGS. 7 and 8,respectively. Each of the terminal and the base station includes atransmitter, a receiver, and a processor. The method of configuringDMRS-related information and the corresponding transmission/receptionoperations of the base station and the terminal are described above, andthe transmitters, receivers, and processors of the base station and theterminal should operate in accordance with the embodiments.

FIG. 7 is a diagram of a terminal 700, according to an embodiment. Asshown in FIG. 7, the terminal may include a receiver 710, a transmitter720, and a processor 730. The receiver 710 and the transmitter 720 maybe collectively referred to as a transceiver. The transceiver cantransmit and receive signals to and from the base station. The signalmay include control information and data. To this end, the transceivermay include an RF transmitter for up-converting the frequency of asignal to be transmitted and amplifying the signal and an RF receiverfor low-noise amplifying a received signal and down-converting thefrequency of the received signal. The transceiver may receive a signalthrough a wireless channel and output the signal to the processor 730,and it may transmit a signal output from the processor 730 through awireless channel. The processor 730 may control a series of operationsso that the terminal can operate as described above. For example, theprocessor 730 may process the DMRS-related information and transmit asignal to the base station through the transmitter 720.

FIG. 8 is a diagram of a base station 800, according to an embodiment.As shown in FIG. 8, the base station may include a receiver 810, atransmitter 820, and a processor 830. The receiver 810 and thetransmitter 820 may be collectively referred to as a transceiver. Thetransceiver can transmit and receive signals to and from thecorresponding terminal. The signal may include control information anddata. To this end, the transceiver may include an RF transmitter forup-converting the frequency of a signal to be transmitted and amplifyingthe signal and an RF receiver for low-noise amplifying a received signaland down-converting the frequency of the received signal. Thetransceiver may receive a signal through a wireless channel and outputthe signal to the processor 830, and it may transmit a signal outputfrom the processor 830 through a wireless channel. The processor 830 maycontrol a series of operations so that the base station can operate asdescribed above. For example, the receiver 810 may receive a signal froma terminal and the processor 830 may configure or determine theDMRS-related information for reception or transmission.

The term “module” used herein may represent, for example, a unitincluding one or more combinations of hardware, software and firmware.The term “module” may be interchangeably used with the terms “logic”,“logical block”, “part” and “circuit”. The “module” may be a minimumunit of an integrated part or may be a part thereof. The “module” may bea minimum unit for performing one or more functions or a part thereof.For example, the “module” may include an ASIC.

Various embodiments of the present disclosure may be implemented bysoftware including an instruction stored in a machine-readable storagemedia readable by a machine (e.g., a computer). The machine may be adevice that calls the instruction from the machine-readable storagemedia and operates depending on the called instruction and may includethe electronic device. When the instruction is executed by theprocessor, the processor may perform a function corresponding to theinstruction directly or using other components under the control of theprocessor. The instruction may include a code generated or executed by acompiler or an interpreter. The machine-readable storage media may beprovided in the form of non-transitory storage media. Here, the term“non-transitory”, as used herein, is a limitation of the medium itself(i.e., tangible, not a signal) as opposed to a limitation on datastorage persistency.

According to an embodiment, the method according to various embodimentsdisclosed in the present disclosure may be provided as a part of acomputer program product. The computer program product may be tradedbetween a seller and a buyer as a product. The computer program productmay be distributed in the form of machine-readable storage medium (e.g.,a compact disc read only memory (CD-ROM)) or may be distributed onlythrough an application store (e.g., a Play Store™). In the case f onlinedistribution, at least a portion of the computer program product may betemporarily stored or generated in a storage medium such as a memory ofa manufacturer's server, an application store's server, or a relayserver.

Each component (e.g., the module or the program) according to variousembodiments may include at least one of the above components, and aportion of the above sub-components may be omitted, or additional othersub-components may be further included. Alternatively or additionally,some components may be integrated in one component and may perform thesame or similar functions performed by each corresponding componentsprior to the integration. Operations performed by a module, aprogramming, or other components according to various embodiments of thepresent disclosure may be executed sequentially, in parallel,repeatedly, or in a heuristic method. Also, at least some operations maybe executed in different sequences, omitted, or other operations may beadded.

While the disclosure has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the scope of the disclosure. Therefore, the scopeof the disclosure should not be defined as being limited to theembodiments, but should be defined by the appended claims andequivalents thereof.

What is claimed is:
 1. A method of a terminal, the method comprising:acquiring first information on an additional demodulation referencesignal (DM-RS) and second information on a maximum number of at leastone symbol for a front-loaded DM-RS for a physical uplink shared channel(PUSCH); receiving, from a base station, downlink control information(DCI) for scheduling a PUSCH; identifying, based on at least one of ahigher layer signaling and the DCI, third information on symbolsduration, fourth information on a mapping type and fifth information ona frequency hopping for the scheduled PUSCH; identifying, based on thefirst information, the second information, the third information, thefourth information and the fifth information, a position of a DM-RSsymbol for at least one of the front-loaded DM-RS and the additionalDM-RS; and transmitting, to the base station, a DM-RS based on theposition of the DM-RS symbol.
 2. The method of claim 1, wherein themapping type for the scheduled PUSCH is one of a first mapping type anda second mapping type, in case that the mapping type for the scheduledPUSCH is the first mapping type, a first position of the at least onesymbol for the front-loaded DM-RS is defined relative to a start of aslot and based on information on a DMRS position, a value 2 or 3 beingdetermined based on the information on the DMRS position, and in casethat the mapping type for the scheduled PUSCH is the second mappingtype, a first position of the at least one symbol for the front-loadedDM-RS is defined relative to a start of resources for the scheduledPUSCH.
 3. The method of claim 2, wherein the first information and thesecond information is sub-configured for at least one of each mappingtype.
 4. The method of claim 1, wherein two consecutive symbols are usedfor the DMRS in case that a number of the at least one symbol for thefront-loaded DM-RS is determined to 2 based on the second information.5. The method of claim 1, wherein the position of the DM-RS symbol ofthe additional DM-RS is identified within a value indicated by the firstinformation, based on the symbol duration for the scheduled PUSCH.
 6. Amethod of a base station, the method comprising: identifying firstinformation on an additional demodulation reference signal (DM-RS) andsecond information on a maximum number of at least one symbol for afront-loaded DM-RS for a physical uplink shared channel (PUSCH);transmitting, to a terminal, downlink control information (DCI) forscheduling a physical uplink shared channel (PUSCH); and receiving, fromthe terminal, a DM-RS based on the position of a DM-RS symbol for atleast one of the front-loaded DM-RS and the additional DM-RS, whereinthe position of the DM-RS symbol is identified based on the firstinformation, the second information, third information on symbolsduration for the scheduled PUSCH, fourth information on a mapping typefor the scheduled PUSCH and fifth information on a frequency hopping forthe scheduled PUSCH, the third information, the fourth information andthe fifth information being identified based on at least one of a higherlayer signaling and the DCI,
 7. The method of claim 6, wherein themapping type for the scheduled PUSCH is one of a first mapping type anda second mapping type, in case that the mapping type for the scheduledPUSCH is the first mapping type, a first position of the at least onesymbol for the front-loaded DM-RS is defined relative to a start of aslot and based on information on a DMRS position, a value 2 or 3 beingdetermined based on the information on the DMRS position, and in casethat the mapping type for the scheduled PUSCH is the second mappingtype, a first position of the at least one symbol for the front-loadedDM-RS is defined relative to a start of resources for the scheduledPUSCH.
 8. The method of claim 7, wherein the first information and thesecond information is sub-configured for at least one of each mappingtype.
 9. The method of claim 6, wherein two consecutive symbols are usedfor the DMRS in case that a number of the at least one symbol for thefront-loaded DM-RS is determined to 2 based on the second information.10. The method of claim 6, wherein the position of the DM-RS symbol ofthe additional DM-RS is identified within a value indicated by the firstinformation, based on the symbol duration for the scheduled PUSCH.
 11. Aterminal in a wireless communication system, the UE comprising: atransceiver; and a processor operably connected to the transceiver, theprocessor configured to: acquire first information on an additionaldemodulation reference signal (DM-RS) and second information on amaximum number of at least one symbol for a front-loaded DM-RS for aphysical uplink shared channel (PUSCH), receive, from a base station,downlink control information (DCI) for scheduling a PUSCH, identify,based on at least one of a higher layer signaling and the DCI, thirdinformation on symbols duration, fourth information on a mapping typeand fifth information on a frequency hopping for the scheduled PUSCH,identify, based on the first information, the second information, thethird information, the fourth information and the fifth information, aposition of a DM-RS symbol for at least one of the front-loaded DM-RSand the additional DM-RS, and transmit, to the base station, a DM-RSbased on the position of the DM-RS symbol.
 12. The terminal of claim 11,wherein the mapping type for the scheduled PUSCH is one of a firstmapping type and a second mapping type, in case that the mapping typefor the scheduled PUSCH is the first mapping type, a first position ofthe at least one symbol for the front-loaded DM-RS is defined relativeto a start of a slot and based on information on a DMRS position, avalue 2 or 3 being determined based on the information on the DMRSposition, and in case that the mapping type for the scheduled PUSCH isthe second mapping type, a first position of the at least one symbol forthe front-loaded DM-RS is defined relative to a start of resources forthe scheduled PUSCH.
 13. The terminal of claim 12, wherein the firstinformation and the second information is sub-configured for at leastone of each mapping type.
 14. The terminal of claim 11, wherein twoconsecutive symbols are used for the DMRS in case that a number of theat least one symbol for the front-loaded DM-RS is determined to 2 basedon the second information.
 15. The terminal of claim 11, wherein theposition of the DM-RS symbol of the additional DM-RS is identifiedwithin a value indicated by the first information, based on the symbolduration for the scheduled PUSCH.
 16. A base station in a wirelesscommunication system, the base station comprising: a transceiver; and aprocessor operably connected to the transceiver, the processorconfigured to control the transceiver to: identify first information onan additional demodulation reference signal (DM-RS) and secondinformation on a maximum number of at least one symbol for afront-loaded DM-RS for a physical uplink shared channel (PUSCH),transmit, to a terminal, downlink control information (DCI) forscheduling a physical uplink shared channel (PUSCH), and receive, fromthe terminal, a DM-RS based on the position of a DM-RS symbol for atleast one of the front-loaded DM-RS and the additional DM-RS, whereinthe position of the DM-RS symbol is identified based on the firstinformation, the second information, third information on symbolsduration for the scheduled PUSCH, fourth information on a mapping typefor the scheduled PUSCH and fifth information on a frequency hopping forthe scheduled PUSCH, the third information, the fourth information andthe fifth information being identified based on the DCI at least one ofa higher layer signaling and,
 17. The base station of claim 16, whereinthe mapping type for the scheduled PUSCH is one of a first mapping typeand a second mapping type, in case that the mapping type for thescheduled PUSCH is the first mapping type, a first position of the atleast one symbol for the front-loaded DM-RS is defined relative to astart of a slot and based on information on a DMRS position, a value 2or 3 being determined based on the information on the DMRS position, andin case that the mapping type for the scheduled PUSCH is the secondmapping type, a first position of the at least one symbol for thefront-loaded DM-RS is defined relative to a start of resources for thescheduled PUSCH.
 18. The base station of claim 17, wherein the firstinformation and the second information is sub-configured for at leastone of each mapping type.
 19. The base station of claim 16, wherein twoconsecutive symbols are used for the DMRS in case that a number of theat least one symbol for the front-loaded DM-RS is determined to 2 basedon the second information.
 20. The base station of claim 16, wherein theposition of the DM-RS symbol of the additional DM-RS is identifiedwithin a value indicated by the first information, based on the symbolduration for the scheduled PUSCH.